Chevrolet 2002 Astro Owner's Manual page 349

Short Trip/City Scheduled Maintenance
j
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.
If you do not use your vehicle under any of these conditions, change the fluid
and filter every 50,000 miles (83 000 km).
j Rotate tires. See "Tire Inspection and Rotation" in the Index for proper
rotation pattern and additional information. (See footnote +.)
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