However, generally speaking, a 2002 Cadillac DeVille would typically use:
* 5W-30 synthetic blend or full synthetic motor oil. This is the most likely recommendation.
Crucially: Don't just rely on this information. Consult your owner's manual. It will specify the exact viscosity (like 5W-30 or another) and the type of oil (synthetic, synthetic blend, conventional) recommended by Cadillac for your specific engine. Using the wrong oil can damage your engine.