1997 Chevrolet Astro Owner's Manual - Page 364

90,000 Miles (150 000 km) 0Change engineoil and filter (or every 12 months, whicheveroccurs first). An Emission Control Service. 0Lubricate chassis components (or every 12 months, whicheveroccurs first). (See footnote#.) 0Check readfront axle fluid level and add fluid as needed. Check constant velocity joints and axle sealsfor leaking. (See footnote **.) For Two-Wheel-Drive vehicles only: Clean andrepack the front wheelbearings (or at each brake relining, whichever occurs first). CJ Change automatic transmission fluid and filter if the vehicleis 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. O 1 If you do not useyour vehicle under anyof these conditions, change the fluid and filter every 30,000 miles (50 000 km).