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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.
If your vehicle has the 4.4L V8 engine
(VIN Code D), use premium unleaded gasoline with
a posted octane rating of 91 or higher. For best
performance, use premium unleaded gasoline with
a posted octane rating of 93. In an emergency, you
can use regular unleaded gasoline with an octane
rating of 87 or higher. If 87 octane fuel is used, do
not perform any aggressive driving maneuvers such
as wide open throttle applications. You may also
hear audible spark knock during acceleration. Refill
your tank with premium fuel as soon as possible to
avoid damaging your engine. If you are using
gasoline rated at 91 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 367 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.
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