Honda Car engines GX640 Owner's Manual page 11

Oxygenated Fuels
Some conventional gasolines are being blended with alcohol or an
ether compound. These gasolines are collectively referred to as
oxygenated fuels. To meet clean air standards, some areas of the
United Sates and Canada use oxygenated fuels to help reduce
emissions.
If you use an oxygenated fuel, be sure it is unleaded and meets the
minimum octane rating requirement.
Before using an oxygenated fuel, try to confirm the fuel's contents.
Some states/provinces require this information to be posted on the
pump.
The following are the EPA approved percentages of oxygenates:
ETHANOL
-(ethyl or grain alcohol) 10% by volume
You may use gasoline containing up to 10%
ethanol by volume. Gasoline containing ethanol
may be marketed under the name "Gasohol".
MTBE
-(methyl tertiary butyl ether) 15% by volume
You may use gasoline containing up to 15% MTBE
by volume.
METHANOL
-(methyl or wood alcohol) 5% by volume
You may use gasoline containing up to 5% metha-
nol by volume as long as it also contains
cosolvents and corrosion inhibitors to protect the
fuel system. Gasoline containing more than 5%
methanol by volume may cause starting and/or
performance problems. It may also damage metal,
rubber, and plastic parts of your fuel system.
If you notice any undesirable operating symptoms, try another
service station or switch to another brand of gasoline.
Fuel system damage or performance problems resulting from the
use of an oxygenated fuel containing more than the percentages of
oxygenates mentioned above are not covered under warranty.
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