GMC 2003 Sonoma Owner's Manual page 280

7
If you choose to perform
the engine oil change
service yourself, be sure
the oil you use 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
for gasoline engines.
I
I
Petroleum Institute certified
You should also use the proper viscosity oil for your
vehicle, as shown in the viscosity chart.
RECOMMENDED SAE VISCOSITY GRADE ENGINE OILS
HOT
WEATHER
COLD
WEATHER
LOOK
FOR MIS
SYMBOL
RECOMMENDED
DO NOT USE SAE 1OW-40, SAE 2OW-50 OR ANY OTHER
VISCOSITY GRADE
OIL
NOT RECOMMENDED
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