Honda 1993 Accord Coupe Owner's Manual page 92

Gasoline
Gasoline
Your Honda operates most effectively on unleaded gasoline with a
pump octane number of 86 or higher. Use of a tower octane gasoline
can cause a persistent, heavy metallic rapping noise in the engine
that can lead to mechanical damage.
We recommend gasolines containing detergent additives that help
prevent fuel system and engine deposits.
Using gasoline containing lead will damage your car's emission
controls. This contributes to air pollution and can void certain parts
of your warranty.
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 States 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)
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)
You may use gasoline containing up to 15% MTBE by volume.