Buick REGAL 1997 Manual page 289

NOTICE:
Don't add too much oil. If your engine has so
much oil that the oil level gets above the
cross-hatched area that shows the proper
operating range, your engine could be damaged.
The engine oil fill cap is located toward the front of the
engine near the yellow-looped engine oil dipstick handle.
Be sure to fill it enough to put the level somewhere in
the proper operating range. Push the dipstick all the way
back in when you're through.
What Kind of Oil to Use
Oils recommended for your vehicle can be identified
by looking for the "Starburst" symbol. This symbol
indicates that the oil has been certified by the American
Petroleum Institute (API). Do not use any oil which
does not carry this Starburst symbol.
If you change your own oil,
be sure you use oil that has
the Starburst symbol on the
front of the oil container. If
you have your oil changed
for you, be sure the oil put
into your engine is
American Petroleum
Tnstitute certified for
gasoline engines.
You should also use the proper viscosity oil for your
vehicle, as shown in the following chart: