Buick 1998 Century Owner's Manual page 274

Engine Oil Additives
Don't add anything to your oil. Your dealer is ready to
advise if you think something should be added.
When to Change Engine Oil
Your vehicle has an Oil Life Monitor. This feature
will let you know when to change your oil and
filter
--
usually between 3,000 miles (5 000 km) and
7,500 miles (12 500 km) since your last oil change.
Under severe conditions, the indicator may come on
before 3,000 miles ( 5 000 km). Never drive your vehicle
more than 7,500 miles (1 2 500 km) or 12 months
(whichever occurs first) without an oil change.
The
system won't detect dust in the oil. So, if you
drive in a dusty area, be sure to change your oil every
3,000 miles (5 000 km) or sooner. Remember to reset
the CHANGE OIL SOON light when the oil has been
changed. For more information, see "Change Oil Soon
Light" in the Index.
How to Reset the CHANGE OIL SC -IN Light
After changing the engine oil, the system must be reset.
With the ignition key in RUN but the engine off, fully
push and release the accelerator pedal slowly three times
within five seconds. If the CHANGE OIL SOON light
flashes, the system is resetting. Turn the key to OFF,
then start the vehicle. If the CHANGE OIL SOON light
comes back on, the system has not reset. Repeat
the procedure.
What to Do with Used Oil
Did you know that used engine oil contains certain
elements that may be unhealthy for your skin and could
even cause cancer? Don't let used oil stay on your skin
for very long. Clean your skin and nails with soap and
water, or a good hand cleaner. Wash or properly throw
away clothing or rags containing used engine oil. (See
the manufacturer's warnings about the use and disposal
of oil products.)
Used oil can be a real threat to the environment. If you
change your own oil, be sure to drain all free-flowing oil
from the filter before disposal. Don't ever dispose of oil
by putting it in the trash, pouring it on the ground, into
sewers, or into streams or bodies of water. Instead,
recycle it by taking it to a place that collects used oil. If
you have a problem properly disposing of your used oil,
ask your dealer, a service station or a local recycling
center for help.