1997 Buick Skylark Owner's Manual - Page 250

What Kind of Oil to Use Oils recommendedfor your vehicle can be identified by looking for the "Starburst" symbol.This symbol indicates thatthe oil has been certified by the American Petroleum Institute (API).Do not use anyoil which does not carry this Starburst symbol. If you change your own oil, be sure you use that has oil the Starburst symbol the on front of the oil container.If you have youroil changed for you, be surethe oil put into your engine is American Petroleum Institute certifiedfor gasoline engines. You should also use the proper viscosity for your oil vehicle, as shown in the following chart: 3100 Engine The engineoil fill cap on the 3 100 engine is located at the front of the engine near the engine oil dipstick. Just fiil it enough to put thelevel somewhere in the proper operating range. Push the dimtick all theway back in when you're through. 6-15