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 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 300for 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 181. 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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