2006 GMC Yukon Owner's Manual - Page 390

When to Add Engine Oil 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. 8.1L Engine All Except 8.1L Engine 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 5-114. 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. 5-16