2003 GMC Sierra 1500 Pickup Owner's Manual - Page 507

50,000 Miles (83000 km) 0 Change automatic transmission fluid and filter if the vehicle's GVWR is over 8600 Ibs, if the vehicle has an Allison transmission or if the vehicle is mainly driven under one or more of these conditions: - In heavy city traffic where the outside 60,000 Miles (100 000 km) 0 Check readfront axle fluid level and add fluid as needed. Check constant velocity joints and axle seals for leaking. 0 Rotate tires. See Tire Inspection and Rotation on page 5-74 for proper rotation pattern and additional information. (See footnote +.) 0 Replace fuel filter. An Emission Control Service (See footnote t.) 0 Replace engine air cleaner filter. An Emission Control Service. 0 Inspect Evaporative Control System. Check all fuel and vapor lines and hoses for proper hook-up, routing and condition. Check that the purge valve works properly, if equipped. Replace as needed. An Emission Control Service. (See footnote t.) 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. Except Allison Transmission: If you do not use your vehicle under any of these conditions, change the fluid and filter at 100,000 miles (166 000 km). C Automatic Transfer Case Only: Change transfer l case fluid. 67,500 Miles (112 500 km) 0 Check readfront axle fluid level and add fluid as needed. Check constant velocity joints and axle seals for leaking. 0 Rotate tires. See Tire Inspection and Rotation on page 5-74 for proper rotation pattern and additional information. (See footnote +.) 52,500 Miles (87 500 km) 0 Check readfront axle fluid level and add fluid as needed. Check constant velocity joints and axle seals for leaking. 0 Rotate tires. See. Tire Inspection and Rotation on page 5-74 for proper rotation pattern and additional information. (See footnote +.) 6-8