Buick 1994 Regal Owner's Manual page 220

These three things are usually included in a doughnut
shaped logo (symbol)
on most containers. If you cannot
find oils with the "starburst" symbol,
you
should look
for oils with the doughnut shaped symbol, containing
the three things noted above.
I
NOTICE:
If you use oils that do not have either the
"starburst" symbol or an API SH or SG
designation, you can cause engine damage not
covered by your warranty.
GM Goodwrench@ oil (in Canada, GM Engine Oil)
meets all the requirements for your vehicle.
Engine Oil Additives
Don't add anything to your oil. Your Buick dealer is
ready to advise if you think something should be added.
When to Change Engine Qil
See if any one of these is true for you:
0
Most trips are less than 4 miles (6 km).
0
It's below freezing outside and most trips are less
than 10 miles
(
16 km).
0
The engine is at low speed most of the time (as in
door-to-door delivery, or in stop-and-go traffic).
0
You tow a trailer often.
Most trips are through dusty places.
If any one of these is true for your vehicle, then you
need to change your oil and filter every 3,000 miles
(5 000 km) or 3 months -- whichever comes first.
If none of them is true, change the oil every 7,500 miles
(12 500 km) or 12 months
-- whichever comes first.
Change the filter at the first oil change and at every
other oil change after that.
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