GMC 2008 Envoy - Manual (Page 311)

If the oil is below the L mark for the L6 engine or the
cross-hatched area at the tip of the dipstick for the
V8 engine, add at least one quart/liter of the
recommended oil. This section explains what kind of oil to
use. For engine oil crankcase capacity, see Capacities
and Specifications on page 5-120.
Notice: Do not add too much oil. If the engine has
so much oil that the oil level gets above the
cross-hatched area (F) that shows the proper
operating range for the L6 engine or above the
cross-hatched area for the V8 engine, 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.
5-17