Hummer 2006 H3 - Manual (Page 286)

When to Add Engine Oil
If the oil is below the cross-hatched area (L), 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 5-100.
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.
See Engine Compartment
Overview on page 5-12
for the location of the
engine oil fill cap.
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.
5-14