When I was at the Porsche dealer a couple of months back...there was a sticker in the engine compartment of a 911 turbo which stated the use of Mobil 1 as the Porsche Oil..... very reaffirming for me since I switched from Redline to Mobil 1 in the last year or so.....whatever the case Synthetics are the way for me... RC 90 90 88 5KCSTQ Rob Carselle - Columbus, OH