2001 GMC Sierra 1500 Pickup Owner's Manual - Page 437

Scheduled Maintenance -- Gasoline Engines 50,000 Miles (83 000 km) j Except Allison Transmission: 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. DATE ACTUAL MILEAGE SERVICED BY: 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). j Allison Transmission Only: If you haven't used your vehicle under severe conditions listed previously and, therefore, haven't changed your automatic transmission fluid, change both the fluid and filter. j Automatic Transfer Case Only: Change transfer case fluid. 52,500 Miles (87 500 km) j Check rear/front axle fluid level and add fluid as needed. Check constant velocity joints and axle seals for leaking. j Rotate tires. See "Tire Inspection and Rotation" in the Index for proper rotation pattern and additional information. (See footnote +.) DATE ACTUAL MILEAGE SERVICED BY: 7-12