Buick 2007 Terraza Owner's Manual page 412

When to Add Engine Oil
If the oil is below the cross-hatched area at the
tip of the dipstick, 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 503.
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.
412
Be sure to add enough oil to put the level
somewhere in the proper operating range in the
cross-hatched area. Push the dipstick all the
way back in when you are through.
See Engine
Compartment Overview
on page 410 for the
location of the engine oil
fill cap.