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If your vehicle has a V8 engine, use premium unleaded
gasoline with a posted octane rating of 91 or higher.
You may also use regular unleaded gasoline rated at
87 octane or higher, but your vehicle’s acceleration may
be slightly reduced, and you may notice a slight audible
knocking noise, commonly referred to as spark knock.
If the octane is less than 87, you may notice a heavy
knocking noise when you drive. If this occurs, use a
gasoline rated at 87 octane or higher as soon as possible.
Otherwise, you might damage your engine. If you are
using gasoline rated at 87 octane or higher and you hear
heavy knocking, your engine needs service.
Gasoline Specifications
At a minimum, gasoline should meet ASTM
specification 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. See Additives on page 5-6
for additional information.
California Fuel
If your vehicle is certified to meet California Emissions
Standards, it is designed to operate on fuels that meet
California specifications. 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
specifications, but emission control system performance
may be affected. The malfunction indicator lamp may
turn on and your vehicle may fail a smog-check test.
See Malfunction Indicator Lamp on page 3-41.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.
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.
5-6