2003 Cadillac DeVille Owner's Manual - Page 287

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 chooseto perform the engine oil change service yourself, be sure the oil you use hasthe starburst symbol on the front of the oil container. If you haveyour oil changed for you, besure the oil put into your engine is American Petroleum Institute certified for gasoline engines. HOT WEATHER LOOK FOR T I HS SYMBOL 1 b 1 1 1 SAE 1OW-30 . ACCEPTABLE IF5W-30ISNOT I RECOMMENDED You should also use the proper viscosity oil for your vehicle, as shown in the viscosity chart. COLD WEATHER DO NOT USESAE 1OW-40, SAE 20W-50 OR ANY OTHER VISCOSITY GRADE OIL NOT RECOMMENDED I I 5-16