2003 Chevrolet Astro Owner's Manual - Page 234
2003 Chevrolet Astro Manual
Page 234 highlights
What Kind of Engine Oil to Use Oils recommended for your vehicle can be identified by looking for the starburst symbol. This symboi indicates that the oii 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 has the starburst symbol on the front of the oil container. If you have your oil changed for you, besure 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 SAE VISCOSITY GRADE ENGINE OILS HOT WEATHER "C t LOOK FOR MIS SYMBOL 3t + 2; - +1 - t 4 - -7 - - 1, 11 1 1 SAE 1OW-30 ACCEPTABLE IF 5W-30 I NOT S AVAILABLE RECOMMENDED 1 5-17 WEATHER DO NOT USE SAE 1OW-40, SAE 2OW-50OR ANY OTHER VlSCOSlN GRADE OIL NOT RECOMMENDED