Buick 2006 LaCrosse - Manual (Page 310)

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 5-98.
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 in the cross-hatched area.
Push the dipstick all the way back in when you are
through.
3.6L V6 Engine
3.8L V6 Engine
5-16