What is the best oil used for 2009 Audi A4?

The best oil for a 2009 Audi A4 is typically a full synthetic oil with a viscosity rating of 5W-40 or 5W-30, as recommended by Audi. Look for oil that meets the VW 502.00 specification, which ensures compatibility with the engine's requirements. Brands like Mobil 1, Castrol, and Liqui Moly are popular choices among Audi owners for their quality and performance. Always consult your owner's manual for specific recommendations based on your driving conditions.