GMC 2015 Sierra Owner's Manual page 480

Footnotes Maintenance
Schedule Additional Required
Services Severe
(1) Or every two years, whichever
comes first. More frequent
replacement may be needed if the
vehicle is driven in areas with heavy
traffic, areas with poor air quality,
or areas with high dust levels.
Replacement may also be needed if
there is a reduction in air flow,
excessive window fogging, or odors.
(2) Check all fuel and vapor lines
and hoses for proper hook-up,
routing, and condition.
(3) Or every four years, whichever
comes first.
(4) 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.
(5) 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.
(6) Or every five years, whichever
comes first. See Cooling System on
page 10-20.
(7) Or every 10 years, whichever
comes first. Inspect for fraying,
excessive cracking, or damage;
replace, if needed.
(8) Or every three years, whichever
comes first.
Service and Maintenance
Special Application
Services
Vehicles with Dual Wheels:
Check dual wheel nut torque at
160, 1 600 and 10 000 km
(100, 1,000 and 6,000 mi) of
driving. Repeat this service
whenever a tire/wheel is
serviced or removed.
Severe Commercial Use
Vehicles Only: Lubricate chassis
components every 5 000 km/
3,000 mi.
Have underbody flushing service
performed. See Underbody
Maintenance in Exterior Care
on page 10-99.
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