Porsche only recommend synthetics (including hydrocracked "synthetics") at 0W-40, 5W-40 and (only for Mobil 1) 5W-50. They mandate 0W-40 where ambient falls below -25C.
Substantial advances made in synthetic oil technology in the last 15 years are a major contributor to their recommendations. From the list, Posting by Phil - join the renewed discussions on the 928uk mail list
The oil discussion continues. Rich Martin reports...
Hi all, Just when you thought it was safe to go back in the mail list - I'm going to stir it up again! You may remember I posted a message that I wrote to Porsche in Stuttgart to get a definitive answer on the oil issue for the 928 model. So they;ve sent some info back which I have scanned for your perusal. I think it may start another argument. For me I think it's quite clear what is and is not recommended and in addition, the viscosity range that is recommended is pretty clear. Interesting I think you'll agree. Rich Manual S4 Note: - Although it says Boxster it applies to all Porsche 4 6 and 8 cylinder engines from 1973