GMC 1995 Suburban Owner's Manual page 301

I
NOTICE:
Use only engine oil with the American Petroleum Institute
Certified For Gasoline Engines "Starburst" symbol. Failure to
use the proper oil can result in engine damage not covered by
your warranty.
GM Goodwrench@ oil (in Canada, GM Engine Oil) tneets a l l the
requirements for your vehicle.
Engine Oil Additives
Don't add anything to your oil. Your GM dealer is ready to advise if you
think something should be added.
When to Change Engine Oil
See if any one of these is true for you:
Most trips are less than 5
t o I O miles
(8
to 16 km). This is particularly
important when outside temperatures are below freezing.
Most trips include extensive idling (such as frequent driving in stop and
go traffic).
0
Most trips are through dusty areas.
You operate your vehicle in dusty areas or off-road frequently.
0
You frequently tow a trailer or use a carrier on top of your vehicle.
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.
Light Duty Emissions:
If none of them is true, change the oil and filter every 7.500 miles
(
12 500
km) or 12 months
-
whichever comes first.
Heavy Duty Emissions:
If none of them is true, change the oil and filter every 6,000 miles
(
1 0 000
km) or 12 months
-
whichever comes first.
Engine Coolant Heater
An engine coolant heater can be a big help if you have to park outside in
very cold weather, 0°F (-I 8°C) or colder. If your vehicle has this option,
see "Engine Coolant Heater''
in
the Index.