Chevrolet TrailBlazer 2007 Owner's Manual page 403

You should look for this on the oil container, and
use only those oils that are identified as meeting
GM Standard GM4718M and have the starburst
symbol on the front of the oil container.
Your vehicle's engine is filled at the factory with a
®
Mobil 1 synthetic oil, which meets all requirements
for your vehicle.
Oils meeting these
requirements should
also have the starburst
symbol on the
container. This symbol
indicates that the oil
has been certified by the
American Petroleum
Institute (API).
Substitute Engine Oil: When adding oil to
maintain engine oil level, oil meeting GM
Standard GM4718M may not be available.
You can add substitute oil designated
SAE 5W-30 with the starburst symbol at
all temperatures. Substitute oil not meeting
GM Standard GM4718M should not be used
for an oil change.
Engine Oil Additives
Do not add anything to the oil. The recommended
oils with the starburst symbol that meet GM
standards are all you will need for good
performance and engine protection.
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