1995 Pontiac Bonneville Owner's Manual - Page 226

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 the vehicle must be on level ground. ~ When to Add Oil If the oil is at or below the ADD line, then you'll need to add some oil. But you must use the right kind. This part explains what kind of oil touse. For crankcase capacity, see "Capacities and Specifications" in the Index. i The engine oil dipstick is directly behind the engine fan area. I NOTICE: Don't add too much oil. your engine has If so much oil that the oil level gets above the cross-hatched area that shows the proper operating range, your engine could be damaged. 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. Just fill it enough to put the levelsomewhere in the proper operating range. Push the dipstick all the way back in when you're through. t To Check 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.