GMC 2011 Sierra Denali Owner's Manual page 450

11-6 Service and Maintenance
Evaporative control system
inspection. Check all fuel
and vapor lines and hoses for
proper hook up, routing, and
condition. Check that the purge
valve, if the vehicle has one,
works properly. Replace as
needed. An Emission Control
Service. The U.S. Environmental
Protection Agency or the
California Air Resources Board
has determined that the failure
to perform this maintenance
item will not nullify the emission
warranty or limit recall liability
prior to the completion of the
vehicle's useful life. We,
however, urge that all
recommended maintenance
services be performed at the
indicated intervals and the
maintenance be recorded.
First Engine Oil Change After
Every 160 000 km/100,000 Miles
Automatic transmission fluid
change (normal service).
See Automatic Transmission
Fluid on page 10 11.
Transfer case fluid change
(normal service). Check
vent hose at transfer case for
kinks and proper installation.
Check to be sure vent hose is
unobstructed, clear, and free of
debris. During any maintenance,
if a power washer is used to
clean mud and dirt from the
underbody, care should be taken
to not directly spray the transfer
case output seals. High pressure
water can overcome the seals
and contaminate the transfer
case fluid. Contaminated fluid
will decrease the life of the
transfer case and should be
replaced.
Spark plug replacement and
spark plug wires inspection.
An Emission Control Service.
First Engine Oil Change After
Every 240 000 km/150,000 Miles
Engine cooling system drain,
flush, and refill (or every
five years, whichever occurs
first). See Engine Coolant on
page 10 16. An Emission Control
Service.
Engine drive belts inspection
for fraying, excessive cracks,
or obvious damage (or every
10 years, whichever occurs
first). Replace, if needed.
An Emission Control Service.