1997 Buick Century Owner's Manual - Page 277

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 at or below the ADD mark, 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 crankcase capacity, see "Capacitiesand Specifications" in the Index. NOTICE: Don't add too much oil. your enginehas so If much oil that the oil level gets above the cross-hatched area that shows the proper operating range, your engine could damaged. be 6-11