Chevrolet 2003 Astro Owner's Manual page 270

If the level is below the bottom of the filler plug hole,
you'll need to add some lubricant. Add enough lubricant
to raise the level to the bottom of the filler plug hole.
What to Use
Refer to the Maintenance Schedule to determine what
kind of lubricant to use. See Part D: Recommended
Fluids and Lubricants on page 6-32.
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