GMC 1996 Sierra Owner's Manual page 253

If your vehicle is certified to meet California Emission
Standards (indicated on the underhood tune-up label),
it
is designed to operate on fuels that meet California
specifications. If such fuels are not available in states
adopting California emissions standards, your vehicle
will operate satisfactorily o n fuels meeting federal
specifications, but emission control system performance
may be affected. The malfunction indicator lamp on
your instrument panel may turn on and/or y o u r vehicle
may fail a smog-check test. I f
this
occurs, return to your
authorized GM dealer for diagnosis to determine the
cause of failure. In the event it
is
determined that the
cause of the condition is the type of fuels used, repairs
may not be covered by your warranty.
In Canada. some gasolines contain an octane-enhancing
additive called MMT. If you use such fuels, your
emission control system performance may deteriorate
and the tnalfunction indicator lamp on your instrument
panel may turn on. If
this happens,
return
t o
your
authorized CM dealer for service.
To provide cleaner air, all gasolines are now required to
contain additives that will help prevent deposits from
forming in your engine and fuel system, allowing your
emission control system to function properly. Therefore,
you should not have to add anything to the fuel. In
addition, gasolines containing oxygenates, such as ethers
and ethanol, and reformulated gasolines may be
available in your area to help clean the air. General
Motors recommends that you use these gasolines if they
comply with the specifications described earlier.
NOTICE:
Your vehicle was not designed for fuel that
contains methanol. Don't use it. It can corrode
metal parts in your fuel system and also damage
plastic and rubber parts. That damage wouldn't
be covered under your warranty.
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