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Fuel
If your vehicle has a diesel engine, see “Diesel Fuel
Requirements and Fuel System” in the DURAMAX
®
Diesel Supplement.
For vehicles with gasoline engines, please read this.
Gasoline
The 8th digit of your vehicle identification number (VIN)
shows the code letter or number that identifies your
engine. You will find the VIN at the top left of the
instrument panel. See Vehicle Identification Number
(VIN) on page 5-122.
If your vehicle has the 5.3L V8 engine (VIN Code Z),
you may use either regular unleaded gasoline or ethanol
fuel containing up to 85% ethanol (E85); also see
Fuel E85 (85% Ethanol) on page 5-8. In all other
gasoline engines, use only regular unleaded gasoline.
Gasoline Octane
For all vehicles, except those with the 6.0L V8 engine
(VIN Code N), 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 6.0L V8 engine (VIN Code N),
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 5-7 for additional
information.
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