United States Air and Radiation EPA420-R-95-001
Environmental Protection April 1995
Agency
&EPA Technical Overview of
the Effects of
Reformulated Gasoline
on Automotive and
Non-Automotive
Engine Performance
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United States Air and Radiation EPA420-R-95-001
Environmental Protection April 1995
Agency
vvEPA Technical Overview of
the Effects of
Reformulated Gasoline
on Automotive and
Non-Automotive
Engine Performance
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I. Executive summary
Reformulated gasolines (RFGs) are similar to many
conventional gasolines in terms of composition, physical and
chemical properties, and effects on engine operation. RFG
results in lower emissions of ozone-forming and toxic chemicals
than typical conventional gasolines.
RFGs are expected to have little or no influence on the
incidence of many engine performance concerns and is expected to
reduce the incidence of some of those concerns. Any such
effects, which at present are hypothetical in nature and have not
been confirmed in the field, would be small and would tend to be
overwhelmed by normal variations in engine operation, ambient
conditions, and fuel quality. Any adverse effects of RFG on
engine performance, which are expected to be extremely rare in
actual use, could be mitigated or eliminated through relatively
simple actions by the engine operator. Furthermore, the
potential problems perceived to be associated with RFG use are
more likely to be the result of improper engine maintenance,
extreme engine operation, operator error, or normal engine wear.
II. Background and benefits of RFG
Congress, through the Clean Air Act Amendments of 1990
(CAAA), required that cleaner-burning gasoline be used in the
nine cities with the worst urban ozone problems in the United
States beginning in 1995. This gasoline, called "reformulated
gasoline" or "RFG", was required to reduce emissions of ozone-
forming compounds and air toxics, such as benzene, when compared
to gasolines in use in 1990. Urban ozone (smog) is formed
through a complex set of chemical reactions involving volatile
organic compounds (VOCs), oxides of nitrogen (NOX), and
sunlight. Urban ozone irritates human lungs, increases breathing
difficulty (particularly for people with asthma, emphysema, or
other lung problems), damages crops and other vegetation, and
degrades paint, rubber, and other materials.
With the input of the oil and auto industries, state and
local governments, oxygenate producers, and environmental
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organizations, the Environmental Protection Agency (EPA) designed
the RFG program to give the oil industry as much flexibility as
possible to produce gasoline which meets these requirements at
the lowest possible cost.
In the first phase of the program, from 1995-1999, cars and
trucks running on reformulated gasoline should produce 15% less
ozone-forming VOCs each mile they are driven. NOX emissions
should not increase over 1990 levels. During this time, RFG use
will also reduce emissions of cancer-causing air toxics from cars
and trucks by 15%. The second phase of the program begins in the
year 2000. In this second phase, RFG use should reduce ozone-
forming emissions by roughly 25%, and air toxics by about 20%
over 1990 levels. NOX should be reduced about 5-7%.
Most programs to reduce pollution from cars and trucks take
years until they become fully effective, since it takes time for
vehicles with new technology to replace older, dirtier vehicles.
Reformulated gasoline, by contrast, reduces pollution from older
and newer cars immediately, which helps make RFG one of the most
convenient and cost-effective ways to clean the air in polluted
cities. As a result, a number of areas have chosen to join the
RFG program to help meet their air quality goals.
III. Similarities and differences between reformulated and
conventional gasolines
Before discussing EPA's findings regarding the various
engine performance concerns, it may be useful to clarify the
similarities and differences between reformulated gasolines and
conventional gasolines (CG).
A. Fuel parameter ranges
As stated earlier, reformulated gasoline is gasoline that
has been "reformulated" to significantly reduce VOC and air
toxics emissions, on average, relative to conventional gasoline.
The term "reformulated", however, refers to slight changes in
the proportion of fuel components in a given fuel, not to extreme
measures where fuel components are totally removed or new,
untested fuel components are included. RFG fuel parameter values
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are well within the ranges of fuel parameter values of existing
gasoline as shown in Table 1.
Gasoline has always been composed of a broad range of
components in varying amounts. The type and amount of each
component affect fuel economy, engine performance, and vehicle
emission levels. The reformulated gasoline program does not
require the creation of entirely new gasoline blends but merely
requires that only lower-emitting gasoline blends be sold in
covered areas.
The following table summarizes the properties of various
gasolines. Conventional gasoline properties are presented in
terms of their average values and the range of values observed in
retail gasolines, including those with oxygenates. For
comparison purposes, the table also shows the average properties
of the most common ethanol blend, which is commonly known as
"gasohol" and contains 10% ethanol by volume. The table also
shows the average properties of "oxyfuels" (gasolines that meet
the requirements of the oxygenated fuels program) and the
reformulated gasolines expected to be produced during 1995-1999.
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Table 1. Comparison of RF6 and Existing Gasoline
Compositions
RVP3
(psi)
T50
(8P)
T90
(°F)
Arom
(vol%)
Olef
(vol%)
Benz
(vol%)
Sulf
(ppm)
MTBE4
(vol%)
EtOH4
(vol%)
Fuel Parameter Values
Conventional
gasoline
Avg1
8.7-S
11.5-W
207
332
28.6'
10.8
1.60
338
--
--
Range2
6.9-
15.1
141-
251
286-
369
6.1-
52.2
0.4-
29.9
0.1-
5.18
10-
1170
0.1-
13.8
0.1-
10.4
Gasohol
(3.5 wt%
oxygen)
Avg
9.7-S
11.5-W
202
316
23.9
8.7
1.60
305
--
10
(national basis)
Oxyfuel
(2.7 wt%
oxygen)
Avg
8.7-S
11.5-W
205
318
25.8
8.5
1.60
313
15
7.7
Phase I
RFG
Avg
7.1/8.0-S
11.5-W
202
316
23.4
8.2
1.0
302
11
5.7
'•Clean Air Act
J1990 Motor Vehicle Manufacturers' Association survey
'Winter (W) higher than Summer (S) to maintain vehicle performance
4Assumes that oxygenates are not present simultaneously in the same
blend. If both MTBE and ethanol are present in a given blend, the total
oxygenate volume is less than that shown for MTBE.
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B. Summary of differences between CG and RFG
Although RFG fuel parameter values are within the ranges of
fuel parameter values of existing gasoline, the reformulated
gasoline regulations do impose limits on certain fuel parameters
in order to achieve the emissions reductions. Specifically, RFG
is required to contain oxygen (supplied by 5.7% ethanol or 11%
MTBE by volume, on average), to have no more than 1% benzene and
to have lower RVP during the summer months than is required in
non-RFG areas. The aromatic content of RFG will also be reduced
to varying degrees to ensure that air toxics emissions are
controlled. Changes in other fuel parameter values will occur
primarily as a result of dilution due to the addition of
oxygenates. These fuel changes are minor, within the range of
existing gasoline, and should have minimal effects on vehicle
performance.
C. Specific RFG Fuel Requirements
1. Reid Vapor Pressure (RVP)
RVP is a measure of how quickly fuel evaporates, or
volatilizes. A higher RVP fuel volatilizes more quickly than a
lower RVP fuel. Higher RVPs are needed under winter conditions
to ensure adequate starting ability. However, in the summer,
high RVPs are not needed since summer temperatures ensure
sufficient volatility. Higher RVP fuels cause higher emissions.
For this reason, summer RVPs have been held at lower levels for
several years. Under the RFG program, summer RVPs will be
reduced even further. This reduction provides the majority of
ozone-forming VOC reductions from RFG.
2. Benzene
Benzene is a proven human carcinogen which is present both
as a fuel component and in exhaust and evaporative emissions. In
RFG, the benzene content of the fuel is limited to roughly 1%
(compared to a typical gasoline average of 1.6%). This limit
reduces emissions of benzene and provides the majority of the 15%
air toxics emission reduction required of RFG.
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3. Oxygenates
Reformulated gasoline is required to contain oxygen. This
oxygen can come from ethanol or from ethers, such as MTBE, ETBE
or TAME. Currently, ethanol and MTBE are the oxygenates
predominately used in RFG.
RFG must on average contain 5.7% ethanol or 11% MTBE, by
volume. However, a given batch of RFG may contain 4.0 to 10.0%
ethanol or 8.3 to 15.0% MTBE, by volume. While every gallon of
RFG must contain oxygenate, RFG contains less oxygenate on
average than is allowed in conventional gasoline (up to 10%
ethanol or 15% MTBE, by volume). However, oxygenate use in CG is
highly dependent on economic factors, that is, whether or not it
is financially advantageous to produce oxygenated gasoline.
On average, RFG is also expected to contain less oxygen than
is found in oxygenated gasoline required in carbon monoxide (CO)
nonattainment areas by the CAAA under a separate program from
RFG. In those areas, the gasoline must contain at least 7.8%
ethanol or 15% MTBE, by volume.
Many of the recent concerns expressed about RFG have
centered on the oxygenate portion of RFG. However, considerable
in-use experience with oxygenates in gasoline exists which
suggests that vehicle performance should, for the most part, be
unaffected by RFG. Oxygenates, particularly ethanol and MTBE,
have been used as gasoline extenders and octane enhancers in
gasoline since the 1970's without notable problems. In the late
1980's, Denver, CO and Phoenix, AZ started the first oxygenated
gasoline programs as a means of reducing CO emissions. Oxygenate
use increased substantially in 1992 with the start of the federal
oxygenated fuel program (for CO control) which was required in
some 39 cities across the country.
In 1990, ethanol was present in nearly 7% of the U.S.
gasoline pool (usually at concentrations of 10%, by volume) and
MTBE was found in nearly 25% of the U.S. gasoline pool (mostly in
smaller concentrations than are required in RFG). Today, MTBE
has a larger market share in CO nonattainment areas than ethanol,
but the choice of oxygenate is highly dependent on local market
conditions. Oxygenates are likely to continue to be used in
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conventional gasoline, primarily as octane enhancers.
4. Other fuel changes
RFG is expected to have levels of other fuel parameters that
are well within the range observed for conventional gasoline.
However, gasoline reformulation is likely to result in small
shifts in some of these parameters. To reduce toxic air
pollutants, RFGs are likely to have lower aromatics levels, on
average, than conventional gasolines, which in turn should reduce
elastomer deterioration rates and deposit formation. RFGs are
expected to have lower olefin levels, which would reduce gum
formation and therefore reduce fuel storage and spark plug
fouling problems. RFGs are also anticipated to have lower levels
of the heaviest gasoline deposits, which in turn should reduce
deposit formation and its associated problems. RFGs are almost
certain to have lower levels of sulfur, which would also reduce
deposit formation, spark plug fouling, engine wear, and corrosion
in the exhaust system, particularly when the second phase of the
RFG program begins in 2000.
D. Seasonal Variations in RFG Composition
Gasoline composition, in general, varies from winter to
summer. For instance, in winter when higher RVPs are required,
greater concentrations of the lighter, higher RVP components are
needed to ensure vehicle startability and performance. The
higher levels of light components tend to dilute the remaining
fuel constituents. In the summer, lower RVP requirements cause a
small shift in gasoline composition as the concentration of
lighter components is reduced. Similarly, in those areas of the
country which require oxygenated gasoline in the winter to reduce
CO emissions, the addition of oxygenate will tend to dilute other
fuel constituents; as oxygenate concentrations are reduced during
the summer, gasoline composition will shift slightly.
Although oxygen and benzene requirements must be met year-
round, RFG composition will also vary from winter to summer. EPA
imposes no constraints on winter RVP levels, so the winter RVPs
of conventional and reformulated gasolines are not expected to
differ. In CO nonattainment areas, the winter gasoline oxygen
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content will generally be the same regardless of whether the area
gets conventional or reformulated gasoline. In summer, when the
RVP of RFG must be lower on average than for CG, compositional
differences between RFG and CG will reflect the oxygen, benzene
and RVP requirements of RFG.
E. Comparison of RFG to California reformulated gasoline
California has its own reformulated gasoline program, which
began with a wintertime oxygenated fuel program in 1992. The
second phase of the California program (CA Phase II) begins in
1996. CA Phase II gasoline has the same oxygen requirement as
RFG. It is somewhat more stringent than the federal RFG program
because limits are imposed on many more fuel parameters (whereas
the Federal RFG program specifies limits only on oxygen, benzene
and RVP). Additionally, until the year 2000, California's limits
on RVP are more stringent than would be required under the
federal RFG program. Beginning in 2000, federal and California
RFGs are likely to have comparable RVP levels as the stricter
Phase II emission reduction requirements take effect for the
federal RFG program.
IV. Overview of RFG-related concerns
Over the last several months, EPA has become aware of a wide
range of concerns regarding the effects of RFG on the performance
of automotive and non-automotive engines. Citizens, engine
manufacturers, and vehicle manufacturers identified three
distinct types of concerns: potential engine performance
problems, potential fuel-related sources of those performance
problems, and concerns regarding the effects of fuel mixtures.
Each of the engine performance concerns raised regarding RFG
can be traced to a wide range of causes, most of which are not
related to fuel characteristics. Furthermore, these problems
have been experienced when using conventional gasoline and hence
are not unique to engines running on RFG. The potential engine
performance problems investigated by EPA are listed below. Each
concern is discussed more fully in Section V.
Potential engine performance problems
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Rough engine operation
Engine overheating
Engine fires
Damaged pistons
Vapor lock
Difficulty in starting the engine
Plugged fuel filters
Fouled spark plugs
Fuel leaks
Potential fuel-related sources of performance problems
• Water absorption by the fuel
• Improper fuel storage and handling practices
• Enleanment
• Reduced Motor Octane
• Materials incompatibility
Fuel mixture concerns
. • Mixtures of oxygenates
• Mixtures of RFG and CG
• Overblends of oxygenates
In addition, a small reduction in fuel economy is expected when
using oxygenate-containing fuels, including RFGs.
This.list comprises the many different concerns that engine
manufacturers have -dealt with for years with regard to fuel
quality issues. None of these concerns are new or unique to the
RFG program. The potential impact of RFG on these concerns and
problems is discussed in the following sections.
V. Assessment of RFQ's effect on engine performance
A. Overview of engine technologies
Before discussing the potential impact of RFG on engine
performance, it may be helpful to provide a brief overview of the
different types of engines and engine technologies in which RFG
and conventional gasoline are used.
• Closed loop v. Open loop; A closed loop control system
contains an oxygen sensor located in the exhaust stream
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which measures the amount of oxygen present and adjusts
the amounts of fuel and air brought into the engine to
maintain a precise air/fuel ratio. As a result,
closed-loop systems automatically compensate for any
oxygen present in the fuel in the form of oxygenates.
Essentially all automobile engines produced since 1981
use closed-loop systems.
An open-loop system has no such control, and the fuel
flow is fixed unless manual adjustments are made to
"enrich" the air/fuel mixture by adding more fuel or
"enlean" the mixture by adding more air. Open-loop
systems will not compensate for oxygen present in the
fuel in the form of oxygenates; as a result, open-loop
engines will run slightly leaner on oxygenated fuels
than on non-oxygenated fuels. Motorcycles,
snowmobiles, and most small engines have open loop
mechanical systems.
• 4-stroke v. 2-stroke: A 4-stroke engine, as in an
automobile, has 4 piston strokes: intake, compression,
power (combustion) and exhaust. In a 2-stroke engine,
exhaust and fuel intake occur during the power stroke.
The operating cycle is thus completed in 2 piston
strokes. Motorcycles, snowmobiles outboard motors, and
.most portable power equipment (e.g., chainsaws) use 2-
stroke engines. Lawn mowers have mostly 4-stroke
engines. All gasoline-powered cars and trucks have 4-
stroke engines.
Gasoline-fueled engines in widespread use today fall into three
broad categories:
• Two-stroke enginaa. all of which are open-loop,
comprise the majority of gasoline-powered small
engines, such as weed and hedge trimmers, snowblowers,
and chainsaws. Essentially all snowmobile engines and
some marine engines fall into this category as well.
Two-stroke engines typically require lubricating oil to
be mixed into the fuel; most operate in a "fuel-rich"
manner, meaning that more fuel is introduced into the
cylinder than can be burned by the oxygen in the
cylinder.
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Four-stroke open-loop engines are used in most
lawnmowers, many marine engines, and some older cars
and light trucks (particularly those produced prior to
the 1981 model year). These engines do not require
lubricating oil to be mixed with the fuel. Most of
these engines tend to run somewhat fuel-rich*
Four-stroke closed-loop engines are found in newer
(1981 and later) model-year cars and light trucks.
These engines .use feedback from an oxygen sensor to
assure that exactly enough air is available to burn all
of the fuel taken in by the engine and do not require
lubricating oil to be mixed with the fuel. Most modern
four-stroke, closed-loop engines are equipped with
sophisticated computer controls to reduce emissions and
optimize engine performance.
B. Engine performance concerns
Vehicle performance problems can occur for a variety of
reasons. Tracing performance problems to a specific cause is
difficult and often impossible. Most of these problems are the
result of non-fuel factors such as vehicle age or mileage,
operating conditions, or maintenance history. In some cases,
performance problems may be related to fuel characteristics. All
of the performance problems brought to EPA's attention in
connection with RFC have been observed on vehicles using
conventional fuel. Furthermore, neither EPA nor the engine
manufacturers have been able to link any of these problems
definitively to .RFG. The ..data available from automotive and
non-automotive engine manufacturers suggest that performance
problems directly attributable to RFG are extremely unlikely.
Given these caveats, the remainder of this section focuses
on potential RFG-related causes of the engine performance
concerns raised in the context of the RFG program.
1. Rough engine operation
Rough engine operation includes stalling, stumbling, rough
idle, engine misfire, or engine knocking. Rough engine operation
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can occur for a variety of reasons, many of which are not fuel-
related. It should be emphasized that these problems' potential
fuel-related causes can and do occur when using conventional
gasoline.
• Inadequate vapor pressure during start-up can make it
difficult to start a cold engine and cause stumbling or
stalling until the engine warms up, particularly in
older model vehicles. Vehicles since the mid-1980's
have been designed to start much more effectively at
cold temperatures. Reformulated gasolines will have
lower RVPs during the summer months than conventional
gasolines, but this difference is not expected to
result in greater start-up problems than is the case
for conventional gasolines since the RVP levels for
reformulated gasoline are still well within the range
of conventional gasolines (as discussed earlier in
Section III). A consumer experiencing start-up
problems should try switching to another gasoline .
supplier to correct the problem, since RVPs can vary
from station to station and from day to day at the same
station. Startability problems that persist when using
different sources of gasoline may indicate a
maintenance problem with the engine.
• As with any gasoline, insufficient fuel octane can
result in engine misfire, knock, dieseling, or rough
idle as discussed in Section C. Such problems may be
corrected by switching to a higher-octane fuel. Rough
operation on premium fuel may be an indicator of
mechanical or other problems with the engine.
2. Engine overheating
Engine overheating is most commonly the result of problems
in the engine's cooling system, operation at extremely high
speeds or under extremely high loads, operation in extremely hot
conditions, or some combination of the three. However, there are
two potential fuel-related contributors to engine overheating,
both of which are discussed in greater detail in Section C.
• Some extremely high-performance open-loop engines
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(particularly air-cooled snowmobile and high-
performance inboard marine engines) supplement the
engine's cooling system by running fuel-rich; such
engines may experience a small increase in operating
temperature due to the enleanment effect of oxygenates
or as a result of operation at lower ambient
temperatures or lower elevations .-- both of which
increase the density of the incoming air and therefore
enlean the fuel/air mixture.
If excessive amounts of water are introduced into an
ethanol-blended gasoline, the water can separate from
the gasoline. This problem is known as "phase
separation;" it is extremely rare and is not unique to
reformulated gasoline. Phase separation can lead to a
range of engine performance problems as discussed in
Section C. (Phase separation can also occur with non-
oxygenated and ether-containing gasolines but is far
less problematic, as discussed in Section C.)
3. Vapor lock
When gasoline vaporizes in the fuel lines, fuel delivery is
restricted or prevented, which can result in power loss or engine
shutdown. This phenomenon is known as vapor lock. High
volatility gasoline and high ambient and engine temperatures can
all contribute to vapor lock. Problems with vapor lock have
diminished greatly in recent years as EPA has required the use of
lower-volatility fuels in the summer and as manufacturers have
improved the design of their fuel systems, notably by increasing
the use of in-line, high-pressure fuel pumps. The RFG program
will further reduce summer RVP levels and thus is expected to
further reduce the incidence of vapor lock.
The fuel lines in some non-automotive engines, notably
certain high-performance inboard marine engines, are located
within an engine compartment that experiences elevated
temperatures during normal operation. According to the
manufacturers, the fuel lines in such applications can experience
temperatures as high as 200-300'P. These temperatures are high
enough to vaporize a substantial portion of the fuel. Since most
oxygenates vaporize at lower temperatures than most other
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gasoline components, fuels containing oxygenates may be somewhat
more prone to vapor lock in such applications than non-oxygenated
gasolines with the same RVP levels. It should be noted that such
problems are hypothetical in nature and have not been reported in
the field. Furthermore, any hypothetical vapor lock problems
associated with oxygenate-containing gasolines such as RFG will
be offset, in whole or in part, by the lower RVP of reformulated
fuels. If vapor lock occurs, the operator should turn off the
engine and allow the engine, fuel lines, and fuel tank to cool
before attempting to re-start the engine.
4. Plugged fuel filters
Plugged fuel filters occur when contaminants block the
filter surface, reducing fuel flow through the filter.
Contaminants can come from several sources. Of particular
relevance to the RFG program is the possibility that improper
fuel handling procedures at fuel distributors or retailers could
result in contaminants being introduced to fuel tanks during
refueling.
Contaminants can also be introduced when certain gasoline
constituents, such as ethanol, behave like solvents and remove or
dissolve components built up in the fuel tank, fuel lines, or
engine and transport them to the fuel filter. The transported
material then plugs the fuel filter. For automotive engines,
this type of fuel filter plugging is expected to be a concern
only in older cars (approximately 1975 vintage) which ran on
leaded gasoline and had lacquer build-up in the fuel lines.
Newer non-automotive engines may experience fuel filter plugging
as well, though for different reasons. Temporary relief from
this problem can be obtained by shutting off the engine and
allowing some time, perhaps 10 to 20 minutes, to pass. The
absence of fuel flow during that time may allow some of the
contaminants to fall off the filter, which should restore engine
performance for a short period of time. However, the only
permanent solution to this problem is to change the fuel filter.
Most non-automotive engine manufacturers recommend changing the
fuel filter annually as part of normal engine maintenance.
Any gasoline stored for long periods of time can
deteriorate, contributing to gum formation which can lead to
14
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plugged fuel filters. If gasoline is not to be used for long
periods of time (greater than 1-2 months), it should be drained
from the fuel tank .or stabilized with a fuel stabilizer.
***Gasoline of poor quality can also cause gum formation. After-
changing the fuel filter, a higher quality gasoline should be
utilized to avoid filter plugging due to gum formation. RFGs are
expected to contain lower levels of olefins, the primary gum-
forming "components in gasoline, and hence are expected to be
slightly less prone to gum formation.
5. Fouled spark plugs
Poor quality gasoline or adverse or lengthy storage
conditions can result in gum formation, as discussed above.
These gums can deposit on spark plugs, thereby fouling them. In
general, gasoline containing heavier components or higher levels
of olefins would be expected to form gums more readily than
gasoline containing less of the heavier components. RFG is
expected to contain lower levels of olefins and heavy components
than existing gasoline, and thus would be less likely to form
gums which could lead to fouled spark plugs. Sulfur deposits can
also foul spark plugs; reformulated gasolines are precluded from
having sulfur levels in excess of 500 ppm and are expected to
contain significantly lower sulfur levels than conventional
gasolines (particularly beginning in 2000), which should reduce
spark plug fouling. In addition, additives are required in all
gasolines for the express purpose of reducing deposits.
6. Engine fires and fuel leaks
Engine fires can result from many different causes. The
primary fuel-related cause of engine fires involves fuel leaks
resulting from materials deterioration, which is discussed in
greater detail in Section C. No confirmed reports have been
received linking oxygenates or other components of RFG to engine
fires, and neither engine nor engine component manufacturers have
indicated that they anticipate any such problems as a result of
the RFG program.
7. Damaged pistons
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A number of engine problems can result in damaged pistons.
Most of these problems are related to normal wear and engine
deterioration or extreme operating conditions, such as extended
operation at wide-open throttle. Poor fuel quality, such as
insufficient octane, can contribute to piston damage,
particularly if engine knock or misfire occurs. RFG is not
expected to increase fuel-related engine damage beyond the levels
experienced with conventional gasolines for most engines.
Regardless of whether RFG or CG is used, consumers experiencing
engine knock or misfire should consider switching to higher-
octane fuel. Knock or misfire that persists even when using
premium fuel may indicate problems with deposit formation, engine
timing, or other engine problems. Consumers experiencing knock
or misfire when using premium gasoline should consult a qualified
service technician.
Inadequate engine lubrication can also cause piston or
cylinder damage. Most cases of inadequate lubrication involve
insufficient engine oil, failure to change engine oil in a timely
manner, oil leaks, or other defects in the engine's lubrication
system. As discussed in Section C, however, contamination of
ethanol-containing gasolines with water can result in phase
separation, which in two-stroke engines can result in a loss of
lubrication.
Some high-performance non-automotive engines, particularly
those used in snowmobiles or marine applications, may be at risk
for damaged pistons or other engine damage if the engine runs too
hot. The most common causes of this problem involve cooling
system defects such as restrictions in air or liquid coolant
flow, prolonged operation at maximum power, or unequal fuel
distribution in the engine. In addition, running the engine with
a leaner-than-normal fuel/air mixture can increase temperatures.
A small enleaning effect occurs when such engines are operated in
cooler .ambient temperatures or when using oxygenated fuels; these
effects are discussed in detail in Section C.
C. Potential fuel-related sources of performance problems
After extensive engineering analysis, investigation of
citizen complaints, and discussion with engine manufacturers, the
following issues were identified as potential fuel-related
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contributors to engine performance problems. It should be noted
that none of these potential problems have been linked
conclusively to real-world engine performance problems;
furthermore, none of these potential problems are unique to RPG.
1. Water absorption/phase separation
-Non-oxygenated gasolines cannot absorb significant amounts
of water. If water is introduced into the fuel tank, it could
separate from the gasoline in a phenomenon called phase
separation. This phenomenon is extremely rare and is most
commonly due to improper fuel storage practices by fuel
distributors or retailers or due to the accidental introduction
of water by the operator during refueling. Water is denser than
gasoline, so if the water separates, it will form a layer beneath
the gasoline. Since water does not burn, and since most engines
obtain their fuel from the bottom of their fuel tank, most
engines will not be able to run once phase separation occurs.
Gasolines containing ethers such as MTBE or ETBE can absorb
slightly more water before phase separation occurs. In such
circumstances, the ethers remain blended into the gasoline. The
situation is more complicated for ethanol-containing fuels. Such
fuels can absorb significantly more water without phase
separation occurring than either non-oxygenated or ether-
containing gasolines. Such fuels can actually help dry out fuel
tanks by blending with the water, allowing it to be combusted.
However, if too much water is introduced into an ethanol-
containing .gasoline (including ethanol-based RFG), the water and
most of the ethanol -- typically 60-70% of the ethanol present in
the original blend -- can separate from the gasoline and the
remaining ethanol. The amount of water that can be absorbed by
ethanol-blended gasolines without phase separation occurring
varies from 0.3 to 0.5 volume percent, depending on temperature.
If phase separation does occur, the ethanol/water mixture would
be drawn into the engine. Some engines may not be able to
operate on this very lean mixture. Other engines may be able to
operate on the mixture but may run rough (see the Enleanment
discussion below).
For certain two-stroke engines, however, phase separation
could lead to more serious problems. In two-stroke engines, the
17
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lubricating oil that is mixed with the fuel will stay in the
hydrocarbon phase if phase separation occurs. The engine may be
able to operate (albeit poorly) on the ethanol-water phase but
will be operating without lubrication and therefore may incur
engine damage. (Lubricating oil also can separate from non-
oxygenated or ether-containing, gasolines, though this problem is
rare and is most likely when the oil/gasoline mixture is stored
for long periods of time without fuel stabilizers.) Because of
the risk of engine damage when operating without proper
lubrication, all two-stroke engine manufacturers recommend
checking the fuel to assure that phase separation has not
occurred.
Some manufacturers expressed concern that ethanol-blended
gasolines might absorb water vapor from the atmosphere, leading
to phase separation. Such problems are of greatest concern for
engines with open-vented fuel tanks that are operated in humid
environments, such as marine engines. However, evidence for this
phenomenon occurring in the real world is limited at best.
States with extensive ethanol programs such as Minnesota have not
reported problems with phase separation due to absorption of
water from the atmosphere. Limited testing with ethanol blends
suggests that the rate of water absorption from the atmosphere is
very slow; it requires several months for open-vented marine fuel
tanks to accumulate sufficient water to make phase separation
possible. Of far greater concern is the accidental introduction
of water during fueling or the presence of water in the fuel tank
prior to the addition of ethanol-blended gasolines. Ether-
blended RPGs are no more susceptible to this .problem than non-
oxygenated gasolines, so consumers concerned about phase
separation may want to restrict their fuel purchases to ether-
blended RFGs.
In addition, consumers can prevent phase separation by
maintaining full fuel tanks when not in use and by purging the
fuel tank of water condensation prior to introducing fuels,
particularly ethanol-containing fuels. Certain over-the-counter
gasoline additives such as "dry gas" (many of which contain
alcohols to keep small amounts of water mixed with the gasoline)
may be helpful. If phase separation does occur, the separated
fuel should be removed from the tank and disposed of properly.
Citizens should not attempt to re-blend phase-separated gasolines
or use it in other engines; instead, they should dispose of the
18
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fuel properly. Moat communities have a household hazardous waste
disposal facility that will accept such fuel.
2. Enleanment
Oxygenates enlean the air/fuel mixture by slightly reducing
the amount of hydrocarbon in the fuel. For instance, an engine
at stoichiometry has an air/fuel ratio of 14.7:1. Gasoline
containing 7.8% ethanol or 11% MTBE (the average level required
under the RFG program) would enlean the mixture to about 15.15:1.
Most newer automobiles are equipped with closed-loop emission
systems, which adjust the amount of air to maintain the desired
air/fuel ratio. Such vehicles will not experience enleanment or
any enleanment-related changes in engine performance.
Open-loop engines (both two-stroke and four-stroke) do not
compensate for the oxygen in the fuel and will run slightly
leaner when operated on RFG or other oxygenate-containing
gasolines. Older, open-loop automobiles have been operated
successfully for years on oxygenated fuels and gasohol without
difficulty and should not be affected adversely by enleanment.
Most non-automotive engines should not experience enleanment-
related operational problems. However, the enleanment effect can
increase engine operating temperatures for open-loop engines that
rely on a -fuel-rich air/fuel mixture to supplement other engine
cooling mechanisms.. A few high-performance engines may require
adjustments to their fuel intake systems to compensate for the
enleanment effect, as discussed below.
The enleanment effect due to oxygenates is similar in
magnitude to the enleanment effect due to operating the engine at
lower ambient temperatures or lower elevations (both of which
increase air density and enlean the fuel/air mixture). As a
result, engines which do not require adjustments to their fuel
intake settings when operated at different altitudes or ambient
temperature conditions are unlikely to require adjustments for
the enleanment effect, though consumers should consult their
operator's manual, dealer, or manufacturer for more detailed
information. According to snowmobile manufacturers, the
adjustment needed to offset the enleanment effect due to
oxygenates is roughly comparable to the adjustment needed to
offset a 5 to IS degree Fahrenheit drop in ambient temperature.
19
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Any adjustments for enleanment should be performed
carefully; overcompensating for enleanment can create additional
engine performance problems and increase emissions. Consumers
should consult the manufacturer or a qualified service technician
to obtain further information about engine adjustments.
3. Improper fuel handling and storage practices
Improper fuel handling and storage practices by fuel
distributors and retailers can create a number of operational
problems, particularly for ethanol-blended RFGs. Basic
precautions must be followed when introducing ethanol-containing
fuels in a fuel distribution system for the first time. Water
must be removed from fuel tanks and fuel lines to prevent phase
separation. The fuel must be prevented from coming into contact
with materials which the fuel might dissolve or otherwise
deteriorate, and filters and screens must be in place to remove
any foreign material before it reaches consumers' fuel tanks.
Failure to do so can result in fuel contamination with fuel
system component materials or deposits, which can in turn impair.
vehicle performance by clogging fuel filters. Both the American
Petroleum Institute and the Renewable Fuels Association have
guidelines for station operators to follow to prevent problems
related to fuel handling and contamination.
4. Reduced Motor Octane
Octane at the pump is determined as the average of the
"Research" and "Motor" octane numbers, or "(R+M)/2". In the
past, oxygenates have been used to increase gasoline octane,
since oxygenates have higher octanes than many gasoline
components. Oxygenates boost research octane to a greater extent
than motor octane. As a result, an oxygenated fuel with the same
posted octane rating as a non-oxygenated fuel may have a slightly
lower motor octane level.
Some non-automotive engine manufacturers have indicated that
their engines respond more strongly to motor octane than research
octane. These manufacturers have expressed concern that the
small reduction in motor octane which could occur as a result of
the oxygen content of RFG could result in a slightly higher
20
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incidence of engine performance problems, such as engine knock,
misfire, dieseling, or rough engine operation. Over time, these
problems can lead to damaged pistons or other engine damage. If
knock, misfire, or dieseling occur, it may be helpful to switch
to a higher octane fuel. If the problem persists, the engine is
most likely suffering from problems unrelated to the fuel and
should be examined by a qualified repair technician.
5. Materials compatibility
There are two distinct types of materials compatibility
problems. Acute failures occur when a substance causes a part to
fail within a very short period of time. Accelerated
deterioration occurs when a substance causes a part to fail
noticeably faster than would have been the case had the part not
been exposed to that substance. Accelerated deterioration can
result from corrosion, chemical reactions between the fuel and
the affected material, or permeation of the fuel through the
material.
New elastomers called fluoroelastomers have been used in
automotive and non-automotive engines since the mid-1980s. These
newer materials are specifically designed to handle all modern
gasolines, including high-aromatic, ethanol-containing, and
ether-containing gasolines within these substances' legally
permissible levels, without experiencing either of the materials
compatibility concerns described above. Fluoroelastomers are far
more resistant to permeation and corrosion than were earlier
elastomers.
Except for the oxygenates, all of the components found in
RFG are natural constituents of gasoline or have been thoroughly
tested for materials compatibility. The oxygenates used in RFG
have also been tested for materials compatibility, and no acute
failures have been noted. Engine and elastomer manufacturers
have indicated that even in older vehicles, any materials
compatibility or deterioration problems which were encountered
would not result in immediate, acute failures of elastomeric
components but rather would result in an increase in
deterioration rates in-use. Furthermore, these oxygenates have
been used for considerable lengths of time in conventional
gasolines without resulting in acute materials failures. Ethanol
21
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and other oxygenates have been used in conventional gasolines
since the mid-1970s as octane enhancers and fuel extenders, and
oxygenated fuels programs have been in place for years in
California, Colorado, and dozens of other carbon monoxide
nonattainment areas without resulting in higher rates of acute
materials failure in the field.
Some materials used in fuel systems tend to degrade over
time, such as the elastomefic materials used to make hoses and
valves. Degradation can occur for many reasons, such as repeated
heating and cooling cycles, normal oxidation by the atmosphere,
or corrosion by road salt or other substances. Fuel composition
can also affect deterioration rates. For example, aromatics (a
natural component of gasoline) can cause some parts to swell. In
addition, degradation of some elastomeric fuel distribution and
engine components may be accelerated by exposure to oxygenates,
particularly ethanol. However, areas covered by the oxygenated
fuels programs mentioned above have not reported higher rates of
materials degradation or failure than areas receiving
conventional gasolines. Furthermore, gasolines with high levels
of aromatics accelerate material degradation to a similar degree
as oxygenated fuels, yet no greater rate of materials failures
has been reported over the past several decades despite
substantial increases in aromatics levels in order to maintain
desired octane levels.
Permeation of fuel through elastomers can accelerate
deterioration. In general, ethanol blends have higher permeation
rates through elastomers than ether blends, which have slightly
higher permeation rates than non-oxygenated gasoline. The higher
permeation rates of oxygenate-containing gasolines are well
within safety limits and are not expected to create performance,
deterioration, or safety problems. No such problems have arisen
during the 15 to 20 years of oxygenate use in the U.S.
Furthermore, engines built since the mid-1980s generally use
fluoroelastomers, which have far lower permeation and
deterioration rates than earlier materials regardless of the
oxygenate type and concentration found in the fuel (within
legally permitted limits).
In summary,, oxygenate-containing conventional or
reformulated gasolines are not believed to cause acute materials
failures or dramatically accelerated rates of materials
22
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deterioration over time. As older engines are retrofitted with
fluoroelastoraeric engine components or replaced by
fluoroelastomer-equipped newer engines, the potential for
oxygenate-related materials deterioration or fuel permeation will
continue to decline. As part of normal vehicle maintenance,
engine owners should inspect their engine and fuel distribution
system for leaks and replace older or leaking components. Owners
of pre-1986 engines (both automotive or non-automotive) with
degraded elastomers and other engine parts should install modern
replacement parts, which are engineered to assure compatibility
with all modern gasolines, including oxygenated gasolines.
D. Fuel mixture concerns
1. Mixtures of RFGs with different oxygenates
Questions have been raised regarding the effects of mixing
RFGs with different oxygenates in consumer fuel tanks. EPA is
not aware of and does not expect performance or driveability
problems for vehicles running on mixtures of different RFGs that
differ from those which may occur for any RFG and which are
discussed above. This expectation is based on several factors:
• Consumers have operated with mixtures of different
oxygenates over the past fifteen years as a result of
refueling at different service stations without
experiencing unusual performance or other problems.
j
• The potential adverse engine performance effects
discussed above are either a function solely of the
oxygen content of the fuel (as in the case of
enleanment) or are related to the concentration of
specific types .of oxygenates (as in the case of
materials deterioration, water absorption/phase
separation, and motor octane levels). None of these
effects are functions of the presence of multiple
oxygenates.
2. Mixtures of RFG and CG
Conventional gasoline may not be sold in areas covered by
23
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the RFG program. However, the program does not control which
gasoline a consumer uses. Thus, a consumer living and driving in
an RFG area may purchase CG outside the area yet drive within the
area with no penalty. Likewise, consumers living in CG areas are
likely, at some point, to fill-up with RFG when in or near an RFG
area, particularly since service stations in CG areas near CG/RFG
boundaries may be supplied with RFG due to the nature of the fuel
distribution system. No unique problems are expected or have
been observed from mixtures of RFG and CG. In fact, mixing RFG
with conventional gasoline would tend to reduce the risk of the
hypothetical effects on engine performance discussed above.
Mixtures of RFG and non-oxygenated gasoline would have lower
concentrations of oxygen and of individual oxygenates than would
be present in RFG alone; mixtures of RFG and oxygenated gasoline
would have lower concentrations of oxygen and individual
oxygenates than would be present in the oxygenated gasoline
alone.
3. Overblends of oxygenates
Concern was expressed that gasoline containing higher levels
of oxygenates than legally allowed (overblends) could cause or
contribute to vehicle performance problems. While gasoline
containing more than 15% MTBE or 10% ethanol (the upper limits
currently permitted in either RFG or CG) could cause or
contribute to the problems discussed here or to other problems,
it is highly unlikely that overblending will occur. First, and
foremost, oxygenates volumes above the waivered limits are
illegal and should not be available in the marketplace. EPA and
the States have a range of enforcement programs designed to
ensure that gasolines sold commercially meet the legal
requirements, and private industry also monitors fuel quality
nationwide. Second, oxygenates tend to be more expensive than
gasoline, so it would not be economically sound for a fuel
producer to overblend. Finally, blending processes at either the
refinery or at the terminal have become far more sophisticated
and less susceptible to error over the past decade, thereby
minimizing overblending (although the risk of accidental
overblending can never be eliminated completely). It should also
be noted that the risk of overblending is not restricted to areas
covered by the RFG program, since oxygenates can be and are
blended in conventional gasolines.
24
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E. Fuel economy
The fuel economy of a vehicle running on RFG would be
expected to decrease slightly because a portion of the high
energy content component (hydrocarbons) is replaced by a lower
energy content component (oxygenate). Auto manufacturers' data
confirm this and suggest a 1-3% drop in fuel economy. A recent
study of the fuel economy of Wisconsin vehicles running on RFG
confirms this range (a 2.8% average loss was reported). Other
factors such as weather conditions and personal driving habits
result in significantly higher fuel economy losses than those
attributable to RFG use. In fact, manufacturers indicate that
the consumer is unlikely to be able to detect a fuel economy loss
which can be solely attributed to RFG.
Citizens have indicated to EPA that they have experienced
substantially greater fuel economy reductions when using RFG than
when using CG. EPA and the automobile and oil industries have
been unable to identify any fuel-related causes for these
reported fuel economy decreases. As mentioned above, controlled
tests conducted in laboratory and on-the-road settings by EPA and
industry consistently show fuel economy decreases in the 1-3%
range. Furthermore, the number of gallons of gasoline sold in
areas covered by either the oxygenated fuels or RFG programs in
their first year of operation has not been substantially larger
than the number of gallons sold in the year before these programs
began, which tends to confirm the controlled studies discussed
above. Nevertheless, EPA is concerned that some citizens may be
experiencing greater decreases in fuel economy than expected,
either because of some unique characteristic of their vehicles or
because of a vehicle-related (as opposed to fuel-related)
problem. EPA and industry are continuing to investigate this
issue.
VI. Summary of Industry-specific non-automotive concerns
EPA discussed RFG-related concerns with manufacturers of
non-automotive engines to identify concerns specific to
particular industries or products. Most of these concerns do not
reflect actual problems encountered with the use of RFG but
instead reflect uncertainty on the part of manufacturers about
25
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the precise effects of different gasolines, including RFGs, on
their engines. Most non-automotive engine manufacturers' owner's
manuals include oxygenated fuels (with the exception of methanol,
which is not permitted in RFG) in their list of acceptable or
recommended fuels and will not void their warranties if an owner
uses oxygenated or reformulated gasoline.
The purpose of this section is to summarize the concerns
expressed by manufacturers of engines for different applications.
It is not intended to evaluate these concerns/ which have been
discussed in prior sections of this report.
A. Marine engines
Manufacturers expressed strong concern about water
absorption and subsequent phase separation of ethanol-containing
gasolines. Phase separation problems can occur in marine engines
at a water content of approximately 0.3-0.5% (3000-5000 ppm) .
Manufacturers recommend not filling a wet. tank (i.e., a tank with
condensation) and either draining the fuel tank or keeping it
full during prolonged storage periods. Manufacturers also
indicated that the risk of water absorption from the atmosphere
by ethanol-blended fuels in open-vented tanks exposed to high-
humidity atmospheric conditions for several months can be
eliminated if tanks are kept at least 2/3 full when not in use.
It should be noted that Minnesota, which has ethanol blended in
the majority of its gasoline, has not reported problems with
water absorption from the atmosphere.
Performance-related concerns other than water absorption
included cold start and engine hesitation with lower-RVP
gasoline. This concern was tempered by manufacturers'
acknowledgement that marine engines often operate on heavily-
weathered fuel with RVP levels lower than those found in RFG.
Manufacturers also expressed concern that high performance
engines might lose several percent of peak power due to RFG's
lower energy density. Manufacturers did not express concern
about detergents.
Marine engine manufacturers did not consider ether-based RFG
to present materials compatibility problems. They did not
consider ethanol-based RFGs to present difficulties for 1986 and
later engines, again because of the use of fluoroelastomeric
26
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components. Manufacturers were somewhat concerned about the
effects of ethanol blends in older engines, though they indicated
that blends of up to 10% ethanol should not present significant
materials compatibility problems.
Manufacturers expressed concern that their engines might
lose performance or experience knock when running on RFG since
oxygenates tend to boost research octane far more than motor
octane. Though posted octane is the average of motor and
research octane, their products respond more strongly to motor
octane. Since experience with RFG in marine applications will
begin with the start of the boating season, no actual cases of
poor performance were reported. Manufacturers suggested
switching to a higher-octane fuel if knock is experienced.
B. Snowmobiles
Snowmobiles tend to operate with a rich air/fuel mixture.
Some manufacturers recommend enriching the air/fuel mixture when
using oxygenate-containing gasolines, just as they recommend
enriching the mixture to compensate for the enleanment effect of
lower temperatures. Enrichment can be accomplished by increasing
the carburetor jet size or changing the ROM chip in fuel-injected
engines. Water.absorption and subsequent phase separation was
also a concern, though not to a greater degree than for
conventional gasolines. Materials compatibility does not appear
to be a significant issue for snowmobile manufacturers as long as
oxygenate concentrations are within the waivered limits.
Minnesota sponsored a snowmobile race on ethanol blends;
participants chose not to make the recommended adjustment yet
experienced the same or lower rate of engine failures (damaged
pistons) as they had in prior years when running on conventional
gasoline (1 blown engine using 10% ethanol va 1-2 blown engines
in a typical year).
C. Motorcycles
Motorcycle manufacturers shared the concerns expressed by
other non-automotive engine manufacturers but had no data linking
RPG use to specific performance.problems. They also expressed
27
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concern about the effect of RFG on cosmetic parts such as highly
polished aluminum and painted surfaces. However, auto
manufacturers' materials testing results do not indicate adverse
affects on automobile non-engine external parts.
D. Other non-automotive 2-stroke engines
Problems were considered most likely to occur in poorly-
maintained older products, products in which the once-per-year
change in fuel filters had not been performed, or products in
which the fuel was not drained during the off-season or had been
allowed to sit for more than 30 days (in which cases water
absorption and subsequent phase separation is more likely, as
well as gum formation). Phase separation is a particular concern
for 2-stroke engines because the engine could run too lean, and
therefore too hot, and at the same time would be running without
lubrication (because the ethanol-water phase would not contain
the lubricating oil). However, no performance nor materials
compatibility problems attributable to RFG have been reported for
small engines. Manufacturers do not anticipate such problems
within the waivered limits for ethers or ethanol.
E. Other non-automotive 4-stroke engines
No concerns were expressed regarding enleanment, materials
compatibility within waivered limits, or fuel aging. No
enrichment is considered necessary to compensate for oxygen
content, except perhaps in the case of snowblowers. However, the
available data are not sufficient to demonstrate the need for
such adjustments.
VII. Conclusions
RFG is very similar to existing or conventional gasoline:
its fuel parameters are well within the range of CG fuel
parameters and its oxygenate content does not exceed the
oxygenate levels of gasolines oxygenated to reduce CO emissions
or conventional gasolines to which oxygenates have been added to
increase octane or extend gasoline. As such, engine performance
and other problems attributable solely to the use of RFG are not
28
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expected. Discussions with both automotive and non-automotive
engine manufacturers have verified this expectation. The engine
performance problems reported to date do not appear to be linked
to fuel characteristics; instead, they appear to be linked to
other conditions, such as operating conditions, normal vehicle
wear, or poor maintenance practices. All potential fuel-related
problems can occur when using conventional gasolines and can be
prevented or addressed, usually with relatively simple consumer
actions.
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APPENDICES
1. Performance Problems/Possible Solutions
2. References
3. Acronyms/Abbreviations
30
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Appendix 1
Performance Problems/Possible Solutions
1.
2.
Performance
Problem
Difficulty
starting
Engine misfire,
knock, dieseling,
rough idle
Fuel -related
Possible Cause
Inadequate vapor
pressure
Insufficient fuel
octane
Possible Solution1
Try another brand
of gasoline
Try a higher
octane fuel
1 The possible solutions listed here have been discussed in
the main document and should be taken as general guidance. To
the best of our knowledge, the possible solutions listed here are
reasonable "fixes" for the associated performance problem,
however, USEPA assumes no responsibility for actions taken based
on these possible solutions. To avoid voiding your warranty,
please consult your owner's manual before taking any action. If
the indicated problem persists, please contact your dealer.
31
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3.
,
4.
Engine
overheating
Vapor lock- -power
loss, engine
shutdown
-Enleanment
effect of
oxygenates
-Enleanment due
to phase
separation
High volatility
fuel
-If possible,
adjust to enrich
air/fuel mixture2
-If phase
separation has
occurred, remove
and dispose of
separated fuel3,
refill tank with
new fuel
-To prevent phase -
separation:
maintain full fuel
tank; purge tank
of condensate
prior to
introducing fuels;
use "dry gas"
Try another brand
of gasoline
2 Adjusting fuel intake settings for vehicles with emissions
standards is a violation of Federal law,if such adjustments
increase emissions beyond permitted levels.
3 Citizens should not attempt to re-blend phase-separated
gasolines or use it in other engines; instead, they should
dispose of the fuel at a facility equipped to handle hazardous
wastes.
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5,
6.
7.
Plugged fuel
filters
Fouled spark
plugs
Blown pistons
-Deposits
loosened by
"solvency"
-Poor quality
gasoline
-Adverse or
lengthy storage
conditions
-Poor quality
gasoline •
-Adverse or
lengthy storage
conditions
-Poor fuel
quality
-Insufficient
fuel octane
-Change filter
-Try another brand
of gasoline
-Drain fuel tanks
prior to long-term
storage
-If not draining
tank, use a fuel
stabilizer
-Try another brand
of gasoline
-Drain fuel tank
prior to long-term
storage
-If not draining
tank, use a fuel
stabilizer
-Try another brand
of gasoline
-Try a higher
octane fuel
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Appendix 2
References4
1) "Cleaner Gasoline Has Come To Your Part of the Country",
American Automobile Manufacturer's Association (AAMA).
2) Technical Bulletin, "Use of Oxygenated Gasolines in Non-
Automotive Engines", Chevron U.S.A. Products Company.
3) Technical Bulletin, "Oxygenated Gasolines and Fuel
Economy", Chevron U.S.A. Products Company.
4) "The Use of Oxygenated Gasoline in Lawn & Garden Power
Equipment, Motorcycles, Boats & Recreational Equipment",
Downstream Alternatives, Inc. (DAI) Informational Document
#941101, November 1994.
5) "Changes in Gasoline II, The Auto Technician's Gasoline
Quality Guide", Downstream Alternatives, Inc., July 1992.
6) "Cleaner Fuels For Cleaner Air, Facts for Motorists
Concerning Colorado's Oxygenated Fuels Program", Colorado
Department of Health, September 1992.
7) Press Release, Portable Power Equipment Manufacturer's
Association, March 7, 1995.
8) Press Release, Briggs & Stratton Corporation, 1995.
9) "Reformulated Gasoline (RFG)", Outboard Service Bulletin,
Outboard Marine Corporation, 1995.
10) "California Phase II Gasoline Evaluation with Small SI
Engines, Reliability Testing Report", Tecumseh Products
Company, Engine and Transmission Group, Prepared for
California Air Resources Board, November 11, 1994.
* For copies of a reference listed here, please contact the
authoring organization directly.
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Appendix 3
Acronyms/Abbreviat ions
AAMA American Automobile Manufacturer's Association
CAA......Clean Air Act
CAAA Clean Air Act Amendments of 1990
CG .Conventional gasoline
CO Carbon monoxide
EPA U.S. Environmental Protection Agency
ETBE Ethyl tertiary butyl ether
ETOH Ethanol
Gasohol..Gasoline containing approximately 10% by volume ethanol
MTBE Methyl tertiary butyl ether
NOX Oxides of nitrogen
Oxyfuel..Oxygenate-containing gasoline for CO nonattainment areas
RFG Reformulated gasoline
RVP Reid vapor pressure
TAME Tertiary amyl methyl ether
T50......Temperature at which 50% of the fuel will be evaporated
T90..'. ...Temperature at which 90% of the fuel will be evaporated
VOC Volatile organic compound
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