Engine Oil Additives; When To Change Engine Oil - GMC 1999 Suburban Owner's Manual

As shown in the chart, SAE 5W
vehicle. However, you can use SAE 10W
_ _
-
to be 0 F ( 18 C) or above. These numbers on an oil
container show its viscosity, or thickness. Do not use
other viscosity oils, such as SAE 20W
NOTICE:
Use only engine oil with the American Petroleum
Institute Certified For Gasoline Engines
"Starburst" symbol. Failure to use the
recommended oil can result in engine damage not
covered by your warranty.
GM Goodwrench R oil meets all the requirements for
your vehicle.
If you are in an area where the temperature falls below
_ _
- -
20 F ( 29 C), consider using either an SAE 5W
synthetic oil or an SAE 0W
easier cold starting and better protection for your engine
at extremely low temperatures.

Engine Oil Additives

Don't add anything to your oil. Your dealer is ready to
advise if you think something should be added.
-
30 is best for your
-
30 if it's going
-
50.
-
30
-
30 oil. Both will provide

When to Change Engine Oil

If any one of these is true for you, use the short trip/city
maintenance schedule:
D
Most trips are less than 5 to 10 miles (8 to 16 km).
This is particularly important when outside
temperatures are below freezing.
D
Most trips include extensive idling (such as frequent
- -
driving in stop and go traffic).
D
You operate your vehicle in dusty areas or
-
off road frequently.
D
You frequently tow a trailer or use a carrier on top of
your vehicle.
D
The vehicle is used for delivery service, police, taxi
or other commercial application.
Driving under these conditions causes engine oil to break
down sooner. 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
If none of them is true, use the long trip/highway
maintenance schedule. Change the oil and filter every
7,500 miles (12 500 km) or 12 months
occurs first. Driving a vehicle with a fully warmed
engine under highway conditions causes engine oil to
break down slower.
yellowblue
whichever occurs first.
--
whichever
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