1997 GMC Sonoma Owner's Manual - Page 361

97,500 Miles (162 500 km) 0Change engine oil and filter (or every 12 months, whichever occurs first). An Emission Control Service. I7 Check readfront axle fluid level and add fluid as needed. Check constant velocity joints and axle seals for leaking. (See footnote * 5 ) 0Rotate tires. See "Tire Inspection and Rotation" in the Index for proper rotation pattern and additional information. (See footnote +.) 0Lubricate chassis components (or every 12 months, whichever occurs first). (See footnote #.)