Gasoline Octane
If your vehicle has the 4.6L V8 engine (VIN Code A),
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.
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. Re ll 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 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 6-6
for 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 3-58. 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.
6-5
Be careful not to spill fuel. Do not top off or over ll
the tank and wait a few seconds after you have
nished pumping before removing the nozzle.
Clean fuel from painted surfaces as soon as
possible. SeeWashing Your Vehicle on page 6-80.
When replacing the fuel cap, turn it clockwise until
it clicks. Make sure the cap is fully installed. The
diagnostic system can determine if the fuel cap has
been left off or improperly installed. This would
allow fuel to evaporate into the atmosphere.
SeeMalfunction Indicator Lamp on page 3-58.
The CHECK GAS CAP message in the Driver
Information Center (DIC) will be displayed if the
fuel cap is not properly installed.
{CAUTION:
If a re starts while you are refueling, do not
remove the nozzle. Shut off the ow of fuel
by shutting off the pump or by notifying the
station attendant. Leave the area immediately.
Notice:If you need a new fuel cap, be sure to get
the right type. Your dealer can get one for you.
If you get the wrong type, it may not t properly.
This may cause your malfunction indicator lamp to
light and may damage your fuel tank and emissions
system. SeeMalfunction Indicator Lamp on
page 3-58.
6-9
In ation - Tire Pressure
Tires need the correct amount of air pressure to operate
effectively.
Notice:Do not let anyone tell you that
under-in ation or over-in ation is all right. It is not.
If your tires do not have enough air (under-in ation),
you can get the following:
Too much exing
Too much heat
Tire overloading
Premature or irregular wear
Poor handling
Reduced fuel economy
If your tires have too much air (over-in ation), you
can get the following:
Unusual wear
Poor handling
Rough ride
Needless damage from road hazardsA Tire and Loading Information label is attached to the
center pillar, below the driver’s door latch. This label
shows your vehicle’s original equipment tires and
the correct in ation pressures for your tires when they
are cold. The recommended cold tire in ation pressure,
shown on the label, is the minimum amount of air
pressure needed to support your vehicle’s maximum
load carrying capacity.
For additional information regarding how much weight
your vehicle can carry, and an example of the tire
and loading information label, seeLoading Your Vehicle
on page 5-33. How you load your vehicle affects
vehicle handling and ride comfort, never load your
vehicle with more weight than it was designed to carry.
When to Check
Check your tires once a month or more.
How to Check
Use a good quality pocket-type gage to check tire
pressure. You cannot tell if your tires are properly in ated
simply by looking at them. Radial tires may look properly
in ated even when they are underin ated. Check the
tire’s in ation pressure when the tires are cold.
Cold means your vehicle has been sitting for at least
three hours or driven no more than 1 mile (1.6 km).
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