CHEVROLET 2009 Impala - Manual (Page 270)

When to Add Engine Oil
If the oil is below the cross-hatched area at the tip of the
dipstick, 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 5-101.
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 5-14 for
the location of the engine
oil fill cap.
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 through.
V6 Engine
V8 Engine
5-18