2003 Buick Century Owner's Manual - Page 231

L I 1 The engine oil fill cap is located toward the front of the engine near the engine oil dipstick handle. See Engine Compartment Overview on page 5-12 for more information on location. When to Add Engine Oil If the oil is at or below the cross-hatched area at the tip of the dipstick, then you'll need to add at least one quart of oil. But you must use the right kind. This part explains what kind of oil to use. For engine oil crankcase capacity, see Capacities and Specifications on page 5-94. Be sure to fill it enough 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're through. Nofice: Don't add too much oil. If your engine has so much oil that the oil level gets above the cross-hatched area that shows the proper operating range, your engine could be damaged. 5-14