GMC Terrain Denali 2015 Owner's Manual page 305

11-6 Service and Maintenance
Footnotes Maintenance
Schedule Additional Required
Services - Normal
(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) Or every five years, whichever
comes first. See Cooling System on
page 10-14.
(6) Or every 10 years, whichever
comes first. Inspect for fraying,
excessive cracking, or damage;
replace, if needed.
(7) Or every three years, whichever
comes first.