Gasoline Octane
Use regular unleaded gasoline with a posted
octane rating of 87 or higher. If the octane
rating is less than 87, you may notice an audible
knocking noise when you drive, commonly
referred to as spark knock. If this occurs, use
a gasoline rated at 87 octane or higher as soon
as possible. If you are using gasoline rated at
87 octane or higher and you hear heavy knocking,
your engine needs service.
Gasoline Speci cations
At a minimum, gasoline should meet
ASTM speci cation D 4814 in the United States
or CAN/CGSB-3.5 in Canada. Some gasolines
may contain an octane-enhancing additive
called methylcyclopentadienyl manganese
tricarbonyl (MMT). General Motors recommends
against the use of gasolines containing MMT.
SeeAdditives on page 437for additional
information.
California Fuel
If your vehicle is certi ed to meet California
Emissions Standards, it is designed to operate
on fuels that meet California speci cations.
See the underhood emission control label.
If this fuel is not available in states adopting
California emissions standards, your vehicle will
operate satisfactorily on fuels meeting federal
speci cations, but emission control system
performance may be affected. The malfunction
indicator lamp may turn on and your vehicle may
fail a smog-check test. SeeMalfunction Indicator
Lamp on page 250. If this occurs, return to
your authorized GM dealer for diagnosis. If it is
determined that the condition is caused by the
type of fuel used, repairs may not be covered
by your warranty.
436
Additives
To provide cleaner air, all gasolines in the
United States are now required to contain additives
that will help prevent engine and fuel system
deposits from forming, allowing your emission
control system to work properly. In most cases,
you should not have to add anything to your
fuel. However, some gasolines contain only the
minimum amount of additive required to meet U.S.
Environmental Protection Agency regulations.
To help keep fuel injectors and intake valves clean,
or if your vehicle experiences problems due to
dirty injectors or valves, look for gasoline that is
advertised as TOP TIER Detergent Gasoline.
Also, your dealer has additives that will help
correct and prevent most deposit-related problems.
Gasolines containing oxygenates, such as
ethers and ethanol, and reformulated gasolines
may be available in your area. General Motors
recommends that you use these gasolines if they
comply with the speci cations described earlier.However, E85 (85% ethanol) and other fuels
containing more than 10% ethanol must not
be used in vehicles that were not designed for
those fuels.
Notice:Your vehicle was not designed for
fuel that contains methanol. Do not use
fuel containing methanol. It can corrode metal
parts in the fuel system and also damage
plastic and rubber parts. That damage would
not be covered under your warranty.
Some gasolines that are not reformulated for low
emissions may contain an octane-enhancing
additive called methylcyclopentadienyl manganese
tricarbonyl (MMT); ask the attendant where you
buy gasoline whether the fuel contains MMT.
General Motors recommends against the use of
such gasolines. Fuels containing MMT can reduce
the life of spark plugs and the performance of
the emission control system may be affected.
The malfunction indicator lamp may turn on.
If this occurs, return to your dealer for service.
437