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 7.0L V8 engine
(VIN Code E), 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 323for 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 200.
322
While refueling, let the cap hang by the tether
below the fuel ll opening.
{CAUTION:
Fuel can spray out on you if you open the
fuel cap too quickly. If you spill fuel and
then something ignites it, you could be
badly burned. This spray can happen if
your tank is nearly full, and is more likely
in hot weather. Open the fuel cap slowly
and wait for any hiss noise to stop.
Then unscrew the cap all the way.
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 411.
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 caphas been left off or improperly installed. This would
allow fuel to evaporate into the atmosphere. See
Malfunction Indicator Lamp on page 200.
The CHECK GAS CAP message will be displayed
on the Driver Information Center (DIC) if the fuel
cap is not properly installed. SeeDIC Warnings and
Messages on page 214for more information.
{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/retailer 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 200.
326
