Chevrolet SUBURBAN 1993 Owner's Manual page 270

If you're using fuel rated at 87 octane or higher and you still hear heavy
knocking, your engine needs service. But don't worry if you hear a little
pinging noise when you're accelerating
or driving up a hill. That's normal and
you don't have to buy a higher octane fuel to get rid of pinging. It's the
heavy, constant knock that means you have
a problem.
What about gasoline with blending materials that contain oxygen, such as
MTBE or alcohol?
MTBE is "methyl tertiary-butyl ether." Fuel that is no more than 15% MTBE is
fine for your vehicle.
Ethanol is ethyl or grain alcohol. Properly-blended fuel that is no more than
10% ethanol is fine for your vehicle.
Methanol is methyl or wood alcohol,
NOTICE
Fuel that is more than 5% methanol is bad
for your vehicfe.
Don't use
'A
It can corrode metal parts
in
your fuel system and also damage plastic
and rubber parts. That damage wouldn't be covered under your warri 'y.
And even at 5% or less, there must be "cosolvents" and corrosion
eventers
in this fuel to help avoid these problems.
Gasolines for Cleaner Air
Your use of gasoline with detergent additives will help prevent deposits from
forming in your engine and fuel system. That helps keep your engine in tune
and your emission control system working properly. It's good for your vehicle,
and you'll be doing your part for cleaner air.
Many gasolines are now blended with materials that called oxygenates.
General Motors recommends that you use gasolines with these blending
materials, such as MTBE and ethanol. By doing so, you can help clean the
air, especially in those parts of the country that have higher carbon monoxide
levels.
In addition, some gasoline suppliers are now producing reformulated
gasolines. These gasolines are specially designed
to
reduce vehicle
emissions. General Motors recommends that you use reformulated gasoline.
By doing so, you can help clean the air, especially
in those parts of the
country that have high ozone levels.
You should ask your service station operators if their gasolines contain
detergents and oxygenates, and if they have been reformulated to reduce
vehicle emissions.
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