GMC 2003 C4C042 Owner's Manual page 277

When to Add Engine Oil
If the oil is at or below the cross
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 engine oil 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
-
cross hatched area upper mark that shows
the proper operating range, your engine could
be damaged.
-
hatched area, then
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.
The engine oil fill cap is
located near the engine oil
dipstick in the engine
compartment, on the
driver's side of the vehicle.
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