After reading hundreds of oil threads/posts on the main Porsche forums, I have come to the conclusion that I am not one bit more informed than if I were just blindly picking one oil from Porsche's A40 list. This is probably because the only two entities with deep information (Porsche, oil manufacturers) keep what they actually know close and personal.
OK. So here are a couple of issues that I wish I could get more solid information on.
Mobil 1. Porsche lists THREE M1 0w-40 oils on its current A40 list:
* "True Life"
What am I supposed to make of this? Is one a "better" (i.e. more wear/heat/change interval-resilient) formula than another?
"Class 4" vs." Class 3 with enhancers".
Here is what I have concluded so far, after yet another talk with an oil company rep (this time Pentosin's point woman): A pure, 100% synth (class IV) is not necessarily or automatically the better choice in extending engine life or postponing catastrophic engine failure (IMS failure, for example) than a class III. It all depends on the specific formulation of additives of the class III oil.
Issue 3: Meeting vs. "exceeding" A40 approval.
Porsche does not specify oils that are "exceeding" A40 specs. It only specifies what oils meet their specs. All of the oils on the list supposedly were put through the same identical rigorous testing at their Weissach center. What gives an oil company the authority to declare that its oil "exceeds" the Porsche spec?
Issue 4: 0w40 vs. 5w-40
If I never see temps below oº F, am I better off with the thicker oil year-round?
In sum, I am still quite suspicious of the many posts all over the net which keep touting mystery oils and oil classifications that will baby my 3.4 M97 engine like no others can. Then they badmouth Mobil 1 as a less than perfectly good oil choice which Porsche only retains because of the lucrative "First Fill" and lther advertising tie-ins between the companies.
To that I say: if M1 were measurably inferior, and if Porsche kept it on its list, Porsche would incur considerable warranty repair cost (not to mention getting a terrible reputation as a manufacturer).