GMC 2012 Sierra - Manual (Page 498)

Black plate (8,1) GMC Sierra Owner Manual - 2012 - CRC - 11/15/11
11-8 Service and Maintenance
Footnotes — Maintenance
Schedule Additional Required
Services — Severe
a) Extreme service. For vehicles
mainly driven off‐road in four‐wheel
drive or used in farming, mining,
forestry, Department of Natural
Resources (DNR), or snow plowing.
b) 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.
c) Or every four years, whichever
comes first.
d) Do not directly power wash 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.
e) Or every five years, whichever
comes first. See Cooling System on
page 10‑18.
f) Or every 10 years, whichever
comes first. Inspect for fraying,
excessive cracking, or damage;
replace, if needed.
Special Application
Services
. Vehicles with Dual Wheels:
Check dual wheel nut torque
at 160 km/100 mi, 1 600 km/
1,000 mi and 9 700 km/6,000 mi.
. Severe Commercial Use
Vehicles Only: Lubricate chassis
components every 5 000 km/
3,000 mi.
. Have underbody flushing service
performed once a year.