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Gasoline Octane
If your vehicle has a V6 engine, 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.
If your vehicle has the 5.3L V8 engine (VIN Code C), 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 3-34. 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.
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