Pontiac 2007 G5 Owner's Manual page 280

When to Add Engine Oil
If the oil is below the MIN (minimum) mark, you
will 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 369.
Notice: Do not add too much oil. If the engine
has so much oil that the oil level gets above the
upper mark that shows the proper operating
range, the engine could be damaged.
280
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 278 for the
location of the engine
oil fill cap.