GMC Acadia 2011 Owner's Manual page 328

10-10 Vehicle Care
Use of Substitute Engine Oils if
dexos is unavailable: In the
event that dexos approved engine
oil is not available at an oil change
or for maintaining proper oil level,
you may use substitute engine oil
displaying the API Starburst symbol
and of SAE 5W-30 viscosity grade.
Use of oils that do not meet the
dexos specification, however,
may result in reduced performance
under certain circumstances.
Viscosity Grade
SAE 5W-30 is the best viscosity
grade for the vehicle. Do not
use other viscosity oils such as
SAE 10W 30, 10W 40, or 20W-50.
Cold Temperature Operation: In
an area of extreme cold, where
the temperature falls below
29°C ( 20°F), an SAE 0W-30
oil should be used. An oil of this
viscosity grade will provide easier
cold starting for the engine at
extremely low temperatures.
When selecting an oil of the
appropriate viscosity grade, be
sure to always select an oil that
meets the required specification,
dexos . See Specification for
more information.
Engine Oil Additives/Engine
Oil Flushes
Do not add anything to the oil.
The recommended oils with the
dexos specification and displaying
the dexos certification mark
are all that is needed for good
performance and engine protection.
Engine oil system flushes are not
recommended and could cause
engine damage not covered by the
vehicle warranty.