GMC 1996 Savana Van Owner's Manual page 226

Your vehicle may have an air bag system. If it does, see
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"Servicing Your Air Bag-Equipped Vehicle" in the
I
Index before attempting to do your own service work.
You should keep a record with all parts receipts and list
the mileage and the date of any service work you
perform. See "Maintenance Record" in the Index.
You can be injured and your vehicle could be
damaged if you try to do service work on a
vehicle without knowing enough about it.
Be sure you have suffkient knowledge,
experience, and the proper replacement
parts and tools before you attempt any
vehicle maintenance task.
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Be sure to use the proper nuts, bolts and
other fasteners. "English" and "metric"
fasteners can be easily confused. If you use
the wrong fasteners, parts can later break
or fall off. You could be hurt.
Fuel (Gasoline Engine)
If your vehicle has a diesel engine, see "Diesel Fuel
Requirements and Fuel System" in the Diesel Engine
Supplement. For vehicles with gasoline engines, please
read this.
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Use regular unleaded gasoline rated at 87 octane,or
higher. At a minimum, it should meet specifications
ASTM D4814 in the United States and CGSB 3.5-M93
in Canada. Improved gasoline specifications have been
developed by the American Automobile Manufacturers
Association (AAMA) for better vehicle performance
and engine protection. Gasolines meeting the AAMA
specification could provide improved driveability and
emission control system protection compared to
other gasolines.
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.
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