2003 GMC Yukon Owner's Manual - Page 478

97,500 Miles (162 500 km) u Check rear/front axle fluid level and add fluid as needed. Check constant velocity joints and axle seals for leaking. u Rotate tires. See Tire Inspection and Rotation on page 5-62 for proper rotation pattern and additional information. (See footnote +.) u 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. u Change transfer case fluid. u Except 8.1L V8 Engine: Inspect Positive Crankcase Ventilation (PCV) valve. An Emission Control Service. 100,000 Miles (166 000 km) u Inspect spark plug wires. An Emission Control Service. u Replace spark plugs. An Emission Control Service. u Change automatic transmission fluid and filter if the vehicle's GVWR is over 8,600 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. 150,000 Miles (240 000 km) u Drain, flush and refill cooling system (or every 60 months since last service, whichever occurs first). See Engine Coolant on page 5-26 for what to use. Inspect hoses. Clean radiator, condenser, pressure cap and neck. Pressure test the cooling system and pressure cap. An Emission Control Service. u Inspect engine accessory drive belt. An Emission Control Service. 6-10