GMC 2010 Sierra - Manual (Page 478)

When to Add Engine Oil
If the oil is below the cross-hatched area at the tip
of the dipstick, add at least one liter/quart of the
recommended oil. This section explains what kind
of oil to use. For engine oil crankcase capacity, see
Capacities and Specifications on page 6‑137.
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 6‑16
for the location of the
engine oil fill cap.
Add enough oil to put the level somewhere in the proper
operating range. Push the dipstick all the way back in
when through.
6-18