Originally Posted by Brucelee

I have heard that and it is conceivable. I don't think any quality synthetic that meets Porsche spec will be an issue.

One thing to note is that the current M1 15W-50 is NOT the same formula that was specd out in 1997. The current version is rumored to be a "make believe syn" rather than a PAO syn.

When all is said and done, I would go with the M1 0W-40, which is apparently still a PAO syn.

Safe vs sorry.

Hope that helps.