Cadillac 2000 DeVille Owner's Manual page 302

CAUTION:
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.
D
Be sure you have sufficient knowledge,
experience, the proper replacement parts
and tools before you attempt any vehicle
maintenance task.
D
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.
Adding Equipment to the Outside
of Your Vehicle
Things you might add to the outside of your vehicle can
affect the airflow around it. This may cause wind noise
and affect windshield washer performance. Check with
your dealer before adding equipment to the outside of
your vehicle.
Fuel
Use premium unleaded gasoline rated at 91 octane or
higher for best performance. You may use middle grade
or regular unleaded gasolines, but your vehicle's
acceleration may be slightly reduced.
It is recommended that the gasoline meet specifications
which have been developed by the American Automobile
Manufacturers Association (AAMA) and endorsed by the
Canadian Motor Vehicle Manufacturers Association for
better vehicle performance and engine protection.
Gasolines meeting the AAMA specification could provide
improved driveability and emission control system
performance compared to other gasolines.
Be sure the posted octane for premium is at least 91
(at least 87 for regular). 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 the recommended octane or
higher and you 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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