1998 GMC Sonoma Owner's Manual - Page 361

Long Trip/Highway Maintenance Schedule 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 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. I f y o ~ 1 not ctse yo~lr' do vehicle ~rnder ofthese conditions, change the fluid crrzy clndjilter every 50,000 miles (83 000 kin).' 0 Replace fuel filter. An Ernission Control Service. (See footnote?.) Cl Replace air cleaner filter. An Ernissiorz Control Service. 0 Rotate tires. See "Tire Inspection and Rotation'?in the Index for proper rotation pattern and additional information. (See footnote +.) 7-39