August 17, 2010

MEMORANDUM

TO: Docket: EPA-HQ-OAR-2010-0448

FROM: Cheryl Caffrey, ASD, Mechanical Engineer

SUBJECT: RFA Summary of Engine Manual Recommendations on Use of Fuel with 10% 

Ethanol

Nonroad engines designs had little changed for decades so it is unclear when they may have 

been modified to account for ethanol blends. As nonroad engines began encountering ethanol in 

the marketplace in the early 1980’s, predominantly in the Midwest region of the United States, 

manufacturers began to provide guidance to their consumers on the use of ethanol blends and/or 

began to make design changes to accommodate E10. Owner’s manuals and organization 

websites provide information to the user about fuel specifications for the engine. The following 

tables list owner manual references from 1988 to present. Table D.4-2 lists several owner 

manual references to the use of ethanol fuel between 1988 and 2000 and it illustrates the range of 

owner notifications on the use of ethanol from no comment to “up to 10%” to “Caution”. 

Table 1: Sample Fuel Specification Recommendations from Several Nonroad 

Owner Manuals 1988-2000

ENGINE 

MANUFACTURE

DATE ON 

SERVICE 

MANUAL

FUEL SPECIFICATION RECOMMENDATION ON FUEL WITH ETHANOL

John Deere Front 

Mower

with Kawasaki 

Overhead Valve 4 

stroke Engine

1988 Gasohol is accepted if not more than 10% ethyl alcohol is in the blend

To help keep water out of fuel, fill tank at end of day’s operation

Mercury Outboard 1997 IMPORTANT: Gasoline containing alcohol (ethanol or methanol) can cause a 

formation of acid during storage and can damage the fuel system. If the gasoline 

being used contains alcohol, it is advisable to drain as much of the remaining 

gasoline as possible from the fuel tank, remote fuel line, and engine fuel system.

Polaris 

Snowmobile

1997 Your Polaris vehicle is calibrated to use non-oxygenated fuel with a minimum 

pump octane of 91 or higher (R+M)/2 method.....

Oxygenated fuel containing a mixture of up to 10% ethanol can be used in your 

Polaris vehicle if these guidelines are followed:

1. When using lower than 91 octane oxygenated fuel, you will need to 

have your dealer make adjustments to your engine and/or fuel system

-Depending on your state and local regulations, your fuel supplier may 

or may not be required to display the type of fuel they are selling. In this 

case you should assume that you are using oxygenated fuels and 

purchase 91 octane or higher (R+M)/2 or have your dealer make the 

necessary adjustments
2. If using oxygenated fuel containing ethanol, additional alcohol deicers or 

water absorbing additives are not required and should not be used.

Bombadier Jet 

Boat

DI 2 stroke engine

2000 CAUTION: The use of a fuel other than regular unleaded fuel can result in craft 

performance deterioration and damage to fuel system and engine components. 

Never experiment with other fuels or fuel ratios. Never use fuel containing 

alcohol, methanol or similar products including naphtha.

Ethanol began increasing in distribution in 2002/2003. Herman and Associates 

performed a survey of nonroad engine owner’s manuals for the Renewable Fuels Association in 

2003 and summarized manufacturer recommendations on the use of ethanol at that time. The 

results differ slightly between and within the recreational vehicle, small engine, marine and 

motorcycle industries. Examples of engine manufacturer fuel recommendations are listed in 

Table III.D.4-3 Note that these contain more detail than those references in Table III.D.4-2. 

This may be due to several factors including the fact that more information was known about 

ethanol use in nonroad engines and the fact that ethanol use was beginning to increase.

Table 2: Examples from 2003 Summary Tables of 

Nonroad Engine Manufacturer Fuel Recommendations

Manufacturer Fuel 

Recommendations

Range of 

Comments on 

Using Fuel with 

Ethanol 

Comments (Example)

Recreational Up to 5%, 

Up to10%

When using oxygenates, carburetor main jet must be one size larger 

than for regular unleaded gas.

Power Approved, 

Up to 10%, 

N/A

Never use gasoline containing methanol, gasohol containing more than 

10% ethanol, gasoline additives, premium gasoline, or white gas. Refer 

to engine manual for gasoline recommendations. Uses Briggs & 

Stratton, Honda or Kohler Engines.

Engine is certified to operate on unleaded gasoline intended for 

automotive use.

Alcohol-blended fuels (called gasohol, ethanol or methanol) can attract 

moisture which leads to separation and formation of acids during 

storage. To avoid engine problems, fuel system should be emptied 

before storage for 30 days or longer. Use fresh fuel next season.

Marine Sport boats: 

Do Not Use

Outboards: 

Up to 10%,

Do not Use, 

Gasoline containing alcohol, methanol (methyl), or ethanol (ethyl), 

may cause wear and damage to bearings, cams, piston(s), piston rings, 

corrosion of metal parts, deterioration of rubber and plastic parts, 

starting, idling, and other engine performance problems.

Gasoline containing alcohol may cause the following problems to your 

outboard and fuel system: corrosion of metal parts, deterioration of 

elastomers and plastic parts, wear and damage of internal engine parts, 

starting and operating difficulties, vapor lock or fuel starvation.

Adverse effects of alcohol are more severe with methanol and are 
worse with increasing content of alcohol.

The use of a fuel other than regular unleaded fuel can result in craft 

performance deterioration and damage to fuel system and engine 

components.

Never use fuel containing alcohol, methanol or similar products 

including naptha.

Motorcycle Up to 10%, 

N/A

Use only premium unleaded gasoline with a minimum pump octane 

rating of 90 ((R+M)/2 method). 

If not satisfied with driveability or fuel economy when using an 

oxygenated fuel, switch back to regular unleaded gasoline or to a 

different brand.

Use only unleaded gasoline, 92 pump octane minimum.

Source: Herman & Associates, Washington, DC: Excerpts from Report on Fuel Recommendations for 2003 Model 

Year, Prepared for RFA

In April , 2009, TCPalm posted the following on the internet regarding use of E10 in boat 

engines1:

WHAT TO DO

1 - Avoid mixing regular fuel with E-10 fuel

2 - Frequently change fuel/water separating filters in fuel system. If none is installed, install one

3 - If it's an older boat, have a marina or service department arrange to clean the fuel tank

4 - If boat will not be used for some time, fill tank to about 95 percent capacity to leave for expansion 

but reduce the chance for condensation.

5 - Never put E-85 in a fuel tank of a boat.

The article also stated that it's the older boats that are affected most by ethanol. Since 

ethanol is a solvent, it dissolves years of buildup off the inside of fuel tanks and fuel lines, in turn 

clogging up the fuel filters.

In 2010, E10 is approximately 80% of the fuel distributed in the country. Owner 

manual samples were received from various industry stakeholders and are summarized in Table

3. They now indicate a general acceptance of E10 use, but no higher ethanol use, and marine 

manufacturers still caution against its use.

 

1

Source: Doug Parylak, service manager, Manatee Marina, Port Salerno, http://www.tcpalm.com/news/2009/apr/17/ethanolblended-fuel-leaves-boaters-fuming/?print=1
Table 3: Owner Manual Recommendations from 2010, Small SI Engines Only

Engine 

Manufacturer

Engine 

Range

Owner Manual Fuel Specifications

Kohler Nonhandhel

d Small SI 

Engines

Gasoline/Alcohol blends

Gasohol (up to 10% ethyl alcohol, 90% unleaded gasoline by volume) is approved as 

a fuel for Kohler engines. Other gasoline/alcohol blends including E20 and E85 are 

not to be used and not approved. Any failures resulting from use of these fuels will 

not be warranted.

Gasoline/Ether blends

Methyl Tertiary Butyl Ether (MTBE) and unleaded gasoline blends (up to a 

maximum of 15% MTBE by volume) are approved as a fuel for Kohler engines. 

Other gasoline/ether blends are not approved.

Honda Class I and 

Class II 

Small SI 

Engines

Refueling...

You may use regular unleaded gasoline containing no more than 10% ethanol (E10) 

or 5% methanol by volume. In addition, methanol must contain cosolvents and 

corrosion inhibitors. Use of fuels with content of ethanol or methanol greater than 

shown above may cause starting and/or performance problems. It may also damage 

metal, rubber and plastic parts of the fuel system. Engine damage or performance 

problems that result from using a fuel with percentages of ethanol or methanol 

greater than shown above are not covered by warranty.

If your equipment will be used on an infrequent or intermittent basis please refer to 

the fuel section of the STORAGE chapter (page 11) for additional information 

regarding fuel deterioration.

ONAN Manufactur

er of 

Generators 

using Small 

SI engines

FUEL RECOMMENDATIONS

Gasoline Generators — Treat the engine of your Onan® or Camp PowerTMgenerator 

to a good grade of regular unleaded gasoline and it’ll purr in response. Gasohol 

(gasoline blended with alcohol) can be used if it contains the correct additive 

mixture percentages:

• Ethanol Blend — Not more than 10% ethanol.

• Methanol Blend — Not more than 5% methanol and must also contain solvents

and corrosion inhibitors.

Briggs and 

Stratton

Class I and 

Class II 

Small SI 

Engines

Fuel Recommendations:

Fuel must meet these requirements:

- Clean fresh unleaded gasoline

- A minimum of 87 octane/87AKI (90 acron)
- Gasoline with up to 10% ethanol (gasohol) or up to 15% MTBE (methyl 

tertiary-butyl ether) is acceptable.

CAUTION: Do not use unapproved gasoline, such as E85. Do not mix oil in 

gasoline or mofidy the engine to run on alternative fuels. This will damage the 

engine components and void the engine warranty. 

Echo Handheld 

engines 

(Small SI)

Alternative fuels, such as E-15 (15% ethanol) or any fuels not meeting ECHO 

requirements are NOT approved for use in ECHO 2-stroke gasoline engines. Use of 

alternative fuels may cause performance problems, loss of power, overheating, fuel 

vapor lock, and unintended machine operation, including, but not limited to, 

improper clutch engagement. Alternative fuels may also cause premature 

deterioration of fuel lines, gaskets, carburetors and other engine components.

Fuel Requirements:

Gasoline – Use 89 Octane (R+M/2) (mid grade or higher) gasoline known to be 

good quality. Gasoline may contain up to 10% ethanol (grain alcohol) or 15% 

MTBE (methyl tertiary-butyl ether). Gasoline containing methanol (wood alcohol) 

is NOT approved.

 References provided by members of the Engine Manufacturers Association 2010