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 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 5-5
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 3-44.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.
Additives
To provide cleaner air, all gasolines in the United States
are now required to contain additives that will help
prevent engine and fuel system deposits from forming,
allowing your emission control system to work
properly. In most cases, you should not have to add
anything to your fuel. However, some gasolines contain
only the minimum amount of additive required to
meet U.S. Environmental Protection Agency regulations.
To help keep fuel injectors and intake valves clean,
or if your vehicle experiences problems due to
dirty injectors or valves, look for gasoline that is
advertised as TOP TIER Detergent Gasoline. Also, your
GM dealer has additives that will help correct and
prevent most deposit-related problems.
Gasolines containing oxygenates, such as ethers and
ethanol, and reformulated gasolines may be available in
your area. General Motors recommends that you use
these gasolines if they comply with the speci cations
described earlier. However, E85 (85% ethanol)
and other fuels containing more than 10% ethanol must
not be used in vehicles that were not designed for
those fuels.
5-5
{CAUTION:
If you spill fuel and then something ignites it,
you could be badly burned. Fuel can spray out
on you if you open the fuel cap too quickly.
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. See
Washing Your Vehicle on page 5-101.
When replacing the fuel cap, turn it clockwise until it
clicks. It will require more effort to turn the fuel cap on
the last turn as you tighten it. 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 3-44.The TIGHTEN FUEL 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 3-54for 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 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 3-44.
5-7
