GMC 2004 Envoy Owner's Manual page 326

5-18
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SAE 5W-30
As shown in the viscosity chart, SAE 5W-30 is best
for your vehicle. However, if it is going to be 0°F
(–18°C) or above and SAE 5W-30 is not available,
you may use SAE 10W-30.
These numbers on an oil container show its
viscosity, or thickness. Do not use other viscosity
oils such as SAE 20W-50.
You should look for this information on the oil container,
and use only those oils that are identified as meeting
GM Standard GM6094M and have the starburst symbol
on the front of the oil container.
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).