Pontiac Sunbird Owner's Manual page 192

Fuel
Use regular unleaded gasoline rated at
87 octane or higher. It should meet
specifications ASTM D4814 in the U.S.
and CGSB 3.5-92 in Canada. These
fuels should have the proper additives,
so you should not have to add anything
to the fuel.
In the U.S. and Canada, it's easy to be
sure you get the right kind of gasoline
(unleaded). You'll see "UNLEADED"
right on the pump. And only unleaded
nozzles will fit into your vehicle's fder
neck.
Be sure the posted octane is at least 87.
If the octane is less than 87, you may get
a heavy knocking noise when you drive.
If it's bad enough, it can damage your
engine.
If you're using fuel rated at 87 octane or
higher and you still hear heavy
knocking, your engine needs service.
But don't worry if you hear a little
pinging noise when you're accelerating
or driving up a hill. That's normal, and
you don't have to buy a higher octane
fuel to get rid of pinging. It's the heavy,
constant knock that means you have a
problem.
Fuel Capacity: 1 5 . 2 U.S. Gallons (57.5 L).
Use unleaded fuel only.
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