2003 GMC Envoy Owner's Manual - Page 312

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 choose to perform the engine oil change service yourself, be sure the oil you use 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. You should also use the proper viscosity oil for your vehicle, as shown in the viscosity chart. RECOMMENDED SAL VISCOSITY GRADE ENGINE OILS HOT WEATHER "F 100 t 80 7 "C + 38 + 27 + 16 t4 + 60 +40+ 20 - -7 18 I - 1 1 0- SAE 5W-30-.. - .. RECOMMENDED / J- J I - LOOU FOR THIS SYMBOL SAE IOW-30 ACCEPTABLE IF 5W-30 IS NOT AVAllABLE COLD WEATHER DO NOT USE SAEIOW-40, SAE 20W-50OR ANY OTHER VISCOSITY GRADE OIL NOT RECOMMENDED 5-17