GMC 2004 Envoy Owner's Manual page 425

Additional Required Services (cont'd)
25,000 50,000 75,000 100,000 125,000 150,000
Service and Miles (Kilometers) (41 500) (83 000) (125 000) (166 000) (207 500) (240 000)
Change automatic transmission
fluid and filter (normal service).
Automatic transfer case only:
Change transfer case fluid.
See footnote (g).
Replace spark plugs.
An Emission Control Service.
V8 engine only: Inspect spark plug
wires. An Emission Control Service.
Engine cooling system service
(or every 5 years, whichever occurs
first). An Emission Control Service.
See footnote (i).
Inspect engine accessory drive belt.
An Emission Control Service.
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