Pontiac 2003 Bonneville Owner's Manual page 277

What Kind of Engine 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.
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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
You should also use the proper viscosity oil for your
vehicle, as shown in the viscosity chart.
SAE 1OW-30 is the viscosity grade recommended for
your vehicle. However, you can use SAE 5W-30 if
it's going to be colder than 60°F (16°C) before your next
oil change. When it is very cold, colder than 0°F
(-18°C) you should use an SAE 5W-30 oil. These
numbers on an oil container show its viscosity,
or thickness. Do not use other viscosity grade oils, such
as SAE 1OW-40 or SAE 20W-50 under any conditions.
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Petroleum Institute certified
for gasoline engines.
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