Chevrolet TrailBlazer 2003 Manual page 301

When to Add Engine Oil
If the oil is at or below the L mark for the L6 engine or
the cross-hatched area at the tip of the dipstick for
the V8 engine, 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 engine oil crankcase
capacity, see Capacities and Specifications on
page 5-98.
Notice: Don't add too much oil. If your engine has
so much oil that the oil level gets above the F
mark that shows the proper operating range for the
L6 engine or above the cross-hatched area for
the V8 engine, your engine could be damaged.
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 in the engine
compartment toward the
passenger's side of
the vehicle. See Engine
Compartment Overview on
page 5-12 for more
information on location.
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