Honda ES6500 Owner's Manual page 23

Occasionally you may hear light "spark knock" or " inging" (metallic
rapping noise) while operating
under heavy loads. T is
IS
no cause for t:
concern.
If spark knock or pin ing occurs at a steady engine speed, under
normal load, change rands of gasoline. If spark knock or pinging %
persists, see an authorized Honda generator dealer.
(1
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 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 asoline containing up to 10% ethanol
by volume.
8 asoline containing ethanol may be
marketed under the name "Gasohol".
MTBE - (methyl tertiary butyl. ether) 15%.by volume
v',o;,","y use gasoline contarnrng up to 15% MTBE by
METHANOL - (methyl or wood alcohol) 5% by volume
You may use gasoline containing up to 5%
methanol 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 dama e or performance problems resulting from the use
of an oxygenate
cr fuel containing more than the percentages of
oxygenates mentioned above are not covered under warranty.
211