1997 GMC Safari Owner's Manual - Page 361

In heavy clry traffic where theoutside 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. - 0Inspect engine accessory drive belt. Replace fuel filter. An Emission Control Service. (See footnote?.) 0Replace air cleaner filter. An Emission Control Service. 0Inspect fuel tank, cap and lines for damage or leaks. Inspect fuel cap gasket for any damage. Replace parts as needed. An Emission Control Service. (See footnote?.) If you do not use your vehicle under any of these conditions, change the fluid and filter every 30,000 miles (50 000 km). 0Rotate tires. See "Tire Inspection and Rotation" in the Index for proper rotation pattern and additional information. (See footnote +.) DATE MILEAGE ACTUAL SERVICED BY: