GMC 2011 Terrain Owner's Manual page 302

10-12 Vehicle Care
Selecting the Right Engine Oil
Selecting the right engine oil
depends on both the proper oil
specification and viscosity grade:
Specification
Use and ask for engine oils with
the dexos certification mark. Oils
meeting the requirements of the
vehicle should have the dexos
certification mark on the container.
This certification mark indicates that
the oil has been approved to the
dexos specification.
This vehicle was filled at the factory
with dexos approved engine oil.
Notice: Use only engine oil
that is approved to the dexos
specification or an equivalent
engine oil of the appropriate
viscosity grade. Engine
oils approved to the dexos
specification will show the dexos
symbol on the container. Failure
to use the recommended engine
oil or equivalent can result in
engine damage not covered by
the vehicle warranty. If you
are unsure whether the oil
is approved to the dexos
specification, ask your service
provider.
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.