Gasoline Octane; Gasoline Specifications; California Fuel - GMC Sierra 2005 Owner's Manual

Gasoline Octane

For all except vehicles with the 6.0L V8 (VIN Code N)
engine, use regular unleaded gasoline with a posted
octane of 87 or higher. If the octane is less than 87, you
may get 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. A little pinging noise when you accelerate or drive
uphill is considered normal. This does not indicate a
problem exists or that a higher-octane fuel is necessary.
If you are using 87 octane or higher-octane fuel and hear
heavy knocking, your engine needs service.
If you have the 6.0L V8 (VIN Code N) engine, use
premium unleaded gasoline with a posted octane of
91 or higher for best performance. You may also
use middle grade or regular unleaded gasoline rated at
87 octane or higher, but your vehicle's acceleration
may be slightly reduced. If the octane is less than 87,
you may get a heavy knocking noise when you drive. If
this occurs, use gasoline rated at 87 octane or higher
as soon as possible. Otherwise, you might damage
your engine.
Gasoline Specifications
It is recommended that gasoline meet specifications
which were developed by automobile manufacturers
around the world and contained in the World-Wide Fuel
Charter which is available from the Alliance of
Automobile Manufacturers at
www.autoalliance.org/fuel_charter.htm. Gasoline
meeting these specifications could provide improved
driveability and emission control system performance
compared to other gasoline.

California Fuel

If your vehicle is certified to meet California Emission
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 3-43. 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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