1998 GMC Sonoma Owner's Manual - Page 353

Long Trip/Highway Maintenance Schedule - I In hilly or mountainous terrain. - When doing frequent trailer towing. - Uses such as found in taxi, police or delivery service. If you do not L L S ~ J O L ~ vehicle urder m y of these conditions,chmge the fluid Imd.filter-every 50,000 miles (83 000 k m ) . 0 Rotate tires. See "Tire Inspection and Rotation" in the Index for proper rotation pattern and additional information. (See footnote+.) 22,500 Miles (37 500 km) El Change engine oil and filter (or every 12 months, whichever occurs first). AIIEmission Contml Service. 0 Lubricate chassis components (or every 12 months, whichever occurs first). (See footnote #.) 0 Check readfront axle fluid level and add fluid as needed. Check constant velocity joints and axle seals for leaking. (See footnote**.) 0 Rotate tires. See "Tire Inspection and Rotation" in the Index for proper rotation pattern and additional information. (See footnote +.) I DATE I 7-31