Gasoline Octane - GMC 2010 Sierra Owner's Manual

The 8th digit of the Vehicle Identification Number (VIN)
shows the code letter or number that identifies the
vehicle's engine. The VIN is at the top left of the
instrument panel. See Vehicle Identification Number
(VIN) on page 6 128.
If the vehicle has the 5.3L V8 engine (VIN Code 0),
the 5.3L V8 engine (VIN Code 3), the 6.0L V8 engine
(VIN Code J), or the 6.2L V8 engine (VIN Code 2),
you can use either unleaded gasoline or ethanol fuel
containing up to 85% ethanol (E85). See Fuel E85 (85%
Ethanol) on page 6 10. In all other gasoline engines,
use only unleaded gasoline. See Gasoline Octane on
page 6 7.

Gasoline Octane

For all vehicles except those with the 6.2L V8 engine
(VIN Code 2), use regular unleaded gasoline with a
posted octane rating of 87 or higher. If the octane rating
is less than 87, an audible knocking noise, commonly
referred to as spark knock, might be heard when
driving. If this occurs, use a gasoline rated at 87 octane
or higher as soon as possible. If heavy knocking is
heard when using gasoline rated at 87 octane or higher,
the engine needs service.
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