1998 GMC Sonoma Owner's Manual - Page 333

I Short TripKity Maintenance Schedule 0 Inspect air cleaner filterif you are driving in dusty conditions. Replace filter if necessary. An Emission C o m d Service. (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 For Two-Wheel-Drive vehicles only: Clean and repack the front wheel bearings (or at each brake relining, whichever occurs first). 0 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 regularlv reaches 90°F (32°C) orhigher. - In hilly or mountainous terrain. - When doing frequent trailer towing. - Uses such as found in taxi, police or delivery service. 7' 1