1998 Oldsmobile Achieva Owner's Manual - Page 243

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. If you have your oil changed for you, be sure the oil put into your engine is American Petroleum Institute certified for gasoline engines. RECOMMENDED SAE VISCOSITY GRADE ENGINE OILS FOR BESTFUELECONOMYANDCOLDSTARTING,SELECTTHELOWEST SAE VISCOSITY GRADE OIL FOR THE EXPECTED TEMPERATURE RANGE. HOT WEATHER LOOK FOR MIS SYMBOL #?34k - SAE 1OW-30 I You should also use the proper viscosity oil for your vehicle, as shown in the following chart: COLD WEATHER DO NOT USE SAE 2OW-50 OR ANYOTHER GRADE OIL NOT RECOMMENDED 6-15