1998 Buick Century Owner's Manual - Page 272

What Kind of Engine Oil to Use Oils recommended for your vehicle can be identified by looking for the "Starburst" symbol. This symbol indicates that the oil has been certified by the American Petroleum Institute (API). Do not use any oil which does not carry this Starburst symbol. If you change your own oil, be sure you use oil that has the Starburst symbol on the front of the oil container. l The engine oil fill cap is located toward the front of the engine near the yellow-looped engine oil dipstick handle. Be sure to 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. If you have your oil changed for you, be sure the oil put into your engine is American Petroleum Institute certified for gasolineengines. You should also use the proper viscosity oil for your vehicle, as shown in the following chart: 6-12