1998 GMC Suburban Owner's Manual - Page 307

NOTICE: Don't add too much oil. If your engine has so much oil that the oil level gets above the upper mark that shows the proper operating range, your engine could be damaged. The engine oil fill cap on the "VORTEC" 5700 is located on the driver's side engine valve cover. The engine oil fill cap on the "VORTEC" 7400 is located on the front of the engine, near the I-ad' lator. 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. 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 chanze your own oil, be sure you use oil that has the Starburst symbol on the front of the oil contgjner. If you have your oil changed for you, be sure the o i l put into your engine is American Petroleum Institute certified for gasoline engines. You should also use the proper viscosity oil for your vehicle. as shown i n the following chart: 6-15