octane CADILLAC DEVILLE 1999 7.G Owners Manual

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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.

Be sure you have sufficient knowledge,
experience, the proper replacement parts
and tools before you attempt any vehicle
maintenance task.

Be sure to use the proper nuts, bolts and
other fasteners. ªEnglishº and ªmetricº
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 may not
accelerate as well.
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. For more information, write to: American
Automobile Manufacturer's Association, 7430 Second
Ave, Suite 300, Detroit MI 48202.
Be sure the posted octane for premium is at least 91 (at
least 89 for middle grade and 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.

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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.
If your vehicle is certified to meet California Emission
Standards (indicated on the underhood emission control
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 on 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 your
vehicle may fail a smog
-check test. (See ªMalfunction
Indicator Lampº in the Index.) If this occurs, return to
your authorized Cadillac 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.
Some gasolines that are not reformulated for low
emissions may contain an octane
-enhancing additive
called methylcyclopentadienyl manganese tricarbonyl
(MMT); ask your service station operator whether or not
the fuel contains MMT. General Motors does not
recommend the use of such gasolines. If fuels containing
MMT are used, spark plug life may be reduced and your
emission control system performance may be affected. The malfunction indicator lamp on your instrument
panel may turn on. If this occurs, return to your
authorized Cadillac dealer for service.
To provide cleaner air, all gasolines in the United States
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
contribute to clean air. General Motors recommends that
you use these gasolines, particularly 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.