Honda WD20X Owner's Manual page 11

Occasionally you may hear light "spark knock" or "pinging" 1 metallic
rapping noise ) while operating under heavy loads. This is no cause for
concern.
If spark knock or pinging occurs at a steady engine speed, under normal
load, change brands of gasoline. If spark knock or pinging persists, see an
authorized Honda water pump dealer.
j-iciq
Running the engine with persistent spark knock or pinging can cause
engine damage.
Running the engine with persistent spark knock or pinging is misuse, and
the Distributor's Limited Warranty does not cover parts damaged by
misuse.
Oxygenated Fuels
Some gasolines are being blended with alcohol or an ether compound to
increase the octane. These gasolines are collectively referred to as
oxygenated fuels. Some areas of the United States use oxygenated fuels
to help meet clean air standards.
If you use an oxygenated fuel, be sure its pump octane rating is 86 or
higher.
Ethanol 1 ethyl or grain alcohol 1
Gasoline containing more than 10% ethanol by volume may cause starting
and/or performance problems. Gasoline containing ethanol may be
marketed under the name "Gasohol".
Methanol ( methyl or wood alcohol)
Gasoline containing methanol must contain cosolvents and corrosion
inhibitors to protect the fuel system. Gasoline containing more than 5%
methanol by volume may cause starting and/or performance problems and
may damage metal, rubber, and rjlastic parts of your fuel system.
MTBE (methyl tertiary butyl ether)
You may use gasoline containing up to 15% MTBE by volume.
Before using an oxygenated fuel, try to confirm the fuel's contents. Some
states (provinces in Canada) require this information to be posted on the
pump. If you notice any undersirable operating symptoms, switch to a
convertional unleaded gasoline. Fuel system damage or performance
problems resulting from the use of an oxygenated fuel are not the
responsibility or Honda and are not covered under warranty.
jTimEq
Oxygenated fuels can damage paint and plastic. Be careful not to spill
fuel when filling your fuel tank. Damage caused by spilled fuel is not
convered under warranty.
9