1996 Buick Park Avenue Owner's Manual - Page 261

It's a good idea to check your engine oil every time you get fuel. In order to get an accurate reading, the oil must be warm and thevehicle must be on level ground. Turn off the engine and give the oil a few minutes to drain back into the oil pan. If you don't, the oil dipstick might not show the actual level. Checking Engine Oil Pull out the dipstick and clean it with a paper towel or cloth, then push it back in all the way. Remove it again, keeping the tip down, and check the level. When to Add Oil If the oil is ator below the ADD mark, then you'll need the to add some oil. But you must use right kind. This part explains what kindof oil to use. For crankcase capacity, see "Capacities and Specifications" in the Index.