1998 Chevrolet Astro Owner's Manual - Page 282

Automatic Transmission Fluid When to Check and Change A good time to check your automatic transmission fluid level is when theengine oil is changed. How to Check Because this operation can be a little difficult, you may choose to have this done at your GM dealership Service Department. ~ If you do it yourself, be sure to follow all the instructions Change boththefluidand filter every 15,000 mileshere,oryoucouldgetafalsereadingonthedipstick. (25 000 km) if the vehicleis mainly driven underone or more of these conditions: 0 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. NOTICE: 0 0 If you do not use your vehicle underany of these conditions, change the fluid and filter every 50,000 miles (83 000 km). See "Scheduled Maintenance Services'' in the Index. Too much or too little fluid can damage your of transmission. Too much can mean that some the fluid could come out and fall on hot engine parts or exhaust system parts, starting a fire. Be sure to get accurate reading if check your an you transmission fluid. 6-20