What type of oil does Cadillac use in the 2003 deville?

The 2003 Cadillac DeVille's recommended oil type depends on the engine it has. There were two main engines offered: a 4.6L Northstar V8 and a 4.6L V8 (non-Northstar).

* For the 4.6L Northstar V8: GM generally recommended using 5W-30 synthetic oil. Always check your owner's manual for the exact specification, as it might specify a particular GM-approved oil.

* For the 4.6L V8 (non-Northstar): This engine also typically used 5W-30, but again, consult your owner's manual for the precise recommendation. It might specify conventional or synthetic blend oil.

Crucially: Your owner's manual is the definitive source for the correct oil type and viscosity for your specific 2003 Cadillac DeVille. The information above is a general guideline, but the specifics might vary slightly.