2002 GMC Sonoma Owner's Manual - Page 402

Short Trip/City Scheduled Maintenance j j 45,000 Miles (75 000 km) (Continued) For Two-Wheel-Drive vehicles only: Clean and repack the front wheel bearings (or at each brake relining, whichever occurs first). 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. - 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). j Inspect engine air cleaner filter if you are driving in dusty conditions. Replace filter if necessary. An Emission Control Service. (See footnote [.) 7-18