1994 Buick Century Owner's Manual - Page 217

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 section explains what kind of oil to use. For crankcase capacity, see "Capacitiesand Specifications" in the Index. What Kind of Oil to Use Beginning midyear 1993, oils of the proper quality for your vehicle will be identified with this new "starburst" symbol, The "starburst" symbol indicates that the oil has been certified by the American Petroleum Institute (API), and is preferred for use in your gasoline engine. You should look for this on the front of the oil container, and use only oils that display this new symbol. NOTICE: Don't add too much oil. your engine hasso If much oil that the oil level gets above the cross-hatched area that shows the proper operating range,your engine could be damaged. I Just fill it enough to put the level somewhere in the proper operating range. Push the dipstick all the way back in when you're through. You should also use the proper viscosity oil for your vehicle, as shown in the following chart: 215