1997 Buick Riviera Owner's Manual - Page 250

When to Add Oil If the oil is at or belowthe ADD mark, thenyou'll need to add at least quart of oil. But you must use one the right kind.This part explains what kind oil to use.For of crankcase capacity, see "Capacities and Specifications" in the Index. What Kind of Oil to Use Oils recommendedfor your vehicle can be identified by looking for the "Starburst" symbol. This symbol indicates that the has been certsed by the American oil Petroleum Institute (API). Do not use anyoil which does not carry this Starburst symbol. If you change your own oil, be sureyou use oil that has the Starburst symbol on the front of the oil container. If you have your changed oil for you, be sure the put oil into your engine is American Petroleum Institute certified for gasoline engines. 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. Add engine oil at the engige oil fill cap nextto the oil dipstick. Be sure tofill it enough to put level somewherein the all the proper operating range. Push the dipstick the way back in when you're through. 1 You should also use the proper viscosity oilfor your vehicle, as shownin the following chart: 6-13