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FWIW, I chose Royal Purple 5w-40 for my Boxster (2.5). I sent off a sample for a VOA and was a little concerned with 726 ppm zinc and 6xx ppm Phosphorus.
I'm strongly considering Redline 5w-40 for my next change.
Even with that said, the RP quieted my engine, and it dose seam to run a little cooler then with the M1.
There are plenty of good oils out there, some are approved, some aren't.
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