GMC 2000 Savana - Manual (Page 267)

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When to Add Engine Oil
If the oil is at or below the ADD mark, 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.
NOTICE:
Don’t add too much oil. If your engine has so
much oil that the oil level gets above the upper
mark that shows the proper operating range,
your engine could be damaged.
The engine oil filler cap is located between the coolant
recovery tank and the air cleaner.
Be sure to fill it enough to put the level somewhere in
the proper operating range. Push the dipstick all the way
back in when you’re through.