1998 Buick Regal Owner's Manual - Page 279

What Kind of Engine Oil to Use Oils recommended for your vehicle canbe 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 Starburstsymbol. If you change your own oil, be sure you use oil that has the Starburst symbol on the front of the oil container. I RECOMMENDED VISCOSITY SAE GRADE ENGINE OILS 1 FOR BEST FUEL ECONOMY AND COLD STARTINC;, SELECT THE LOWEST SAE VISCOSITY GRADE OIL FOR THE EXPECTED TEMPERATURE RANGE. HOT WEATHER ' T C ) LOOK FOR THIS SYMBOL If you have your oil changed for you, be sure the oil put into your engine is American Petroleum Institute certified for gasoline engines. should also use the You proper viscosity oil foryour vehicle, as shown in the following chart: L SAE 1OW-30 PREFERRED above 0°F (-18°C) COLD WEATHER DO NOT USE SAE 2OW-50 OR ANY OTHER FD 6-15