spark plugs replace GMC SIERRA 2001 Owner's Manual

Scheduled Maintenance -- Gasoline Engines
7-16
100,000 Miles (166 000 km)

Inspect spark plug wires.
An Emission Control Service.

Replace spark plugs.
An Emission Control Service.

Change automatic transmission fluid and filter if the vehicle's GVWR
is over 8600 lbs. or if the vehicle is mainly driven under one or more of
these conditions:
± In heavy city traffic where the outside temperature regularly reaches
90
F (32
C) or higher.
± In hilly or mountainous terrain.
± When doing frequent trailer towing.
± Uses such as found in taxi, police or delivery service.
If you haven't used your vehicle under severe service conditions listed
previously and, therefore, haven't changed your automatic transmission fluid,
change both the fluid and filter.
Automatic Transfer Case Only: Change transfer case fluid.
Inspect Positive Crankcase Ventilation (PCV) valve.
An Emission Control Service. ACTUAL
SERVICED BY:MILEAGE
DATE