Here is what I know about synthetic oil and the VR6. VR6 is designed to run in the 210-240 degree range. Synthetic oil is designed to run cooler, and except under extreme conditions, rarely reaches 240 degrees. I have never had a VW tech reccomend synthetic oil. I run petroleum based 20w50, Valvoline The dealer put Valvoline 15w40 durablend in my car, it is a synthetic/petroleum blend. Billy T.