Pontiac 1999 Firebird - Manual (Page 261)

yellow blue
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Checking Engine Oil
Pull out the dipstick and clean it with a paper towel or
cloth, then push it back in all the way. Remove it again,
keeping the tip down, and check the level.
3800 V6 Engine
5.7L V8 Engine
When to Add Engine Oil
If the oil is at or below the ADD line, then you’ll need
to add at least one quart of oil. But you must use the
right kind. This part explains what kind of oil to use. For
crankcase capacity, see “Capacities and Specifications”
in the Index.