Chevrolet 2004 Astro Owner's Manual page 331

50,000 Miles (83 000 km)
If you have not used your vehicle under severe
service conditions listed previously and, therefore,
have not changed your automatic transmission fluid,
change both the fluid and filter.
Change transfer case fluid.
51,000 Miles (85 000 km)
Change engine oil and filter (or every 3 months,
whichever occurs first). An Emission Control Service.
Lubricate chassis components (or every 3 months,
whichever occurs first). (See footnote #.)
54,000 Miles (90 000 km)
Change engine oil and filter (or every 3 months,
whichever occurs first). An Emission Control Service.
Lubricate chassis components (or every 3 months,
whichever occurs first). (See footnote #.)
Rotate tires. See Tire Inspection and Rotation on
page 5-62 for proper rotation pattern and additional
information. (See footnote +.)
57,000 Miles (95 000 km)
Change engine oil and filter (or every 3 months,
whichever occurs first). An Emission Control Service.
Lubricate chassis components (or every 3 months,
whichever occurs first). (See footnote #.)
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