Chevrolet 2007 Colorado Owner's Manual page 334

When to Add Engine Oil
If the oil is below the cross-hatched area (L),
you need to add at least one quart/liter of oil.
But you must use the right kind. This section
explains what kind of oil to use. For engine
oil crankcase capacity, see Capacities and
Specifications on page 437.
Notice: Do not add too much oil. If the
engine has so much oil that the oil level
gets above the cross-hatched area that
shows the proper operating range, the
engine could be damaged.
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Be sure to add enough oil to put the level
somewhere in the proper operating range.
Push the dipstick all the way back in when
you are through.
See Engine
Compartment Overview
on page 332 for the
location of the engine
oil fill cap.