2000 GMC Sonoma Owner's Manual - Page 352

Long Trip/Highway Scheduled Maintenance - In hilly or mountainous terrain. - When doing frequent trailer towing. - Uses such as found in taxi, police or delivery service. If you do not use your vehicle under any of these conditions, change the fluid and filter every 50,000 miles (83 000 km). Replace fuel filter. An Emission Control Service. (See footnote [.) j Replace engine air cleaner filter. An Emission Control Service. j Rotate tires. See "Tire Inspection and Rotation" in the Index for proper rotation pattern and additional information. (See footnote +.) j 97,500 Miles (162 500 km) j Change engine oil and filter (or every 12 months, whichever occurs first). An Emission Control Service. j Lubricate chassis components (or every 12 months, whichever occurs first). (See footnote #.) j Check rear/front axle fluid level and add fluid as needed. Check constant velocity joints and axle seals for leaking. (See footnote **.) 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: 7-40