1999 GMC Sonoma Owner's Manual - Page 338

yellowblue Long Trip/Highway Scheduled Maintenance 7,500 Miles (12 500 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: 15,000 Miles (25 000 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 Change automatic transmission fluid and filter 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. DATE ACTUAL MILEAGE SERVICED BY: 7-30