1998 Pontiac Grand Prix Owner's Manual - Page 291
1998 Pontiac Grand Prix Manual
Page 291 highlights
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 has been certified by American oil the Petroleum Institute (API).Do not use any oil which does not carry this Starburst symbol. 3800 or 3800 Supercharged Engine Be sure to fill it enough to put the level somewhere in ;v "i . f the proper operating range. Push the dipstick all the way back in when you're through. If you change your own oil, be sure you useoil that has the Starburst symbol on the front of the oil container. If you have your oil changed for you, be sure the put into oil your engineis American Petroleum Institute certifiel d for gasoline engines. You should also use the proper viscosity oil your for vehicle, as shown in the following chart: 6-16