I did a little sleuthing. I will also reach out to my moles in the labs (exxonmobil and BPL).
The new Mobil1 ESP meet's Porsche's going forward C40 standard but explicitly not backward compatible with A40. I need to read the data more carefully to guess why. the simple answer is, of course, "because Porsche says so".
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www.mobil.com]
The replacement for the old Mobil1 0W40 is called FS. It meets Porsche A40. Note it has a higher HTHS (possibly the spec we care most about since it measures film strength when hot and under pressure). It meets ACEA A3, which was always the heart of A40 anyway.
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www.mobil.com]
I find it curious that they do not specify the HTHS spec, while they do for the other oil that does NOT meet A3 (3.53 which is below the magic 3.8).
The new FS 5W40 also meets A40. By starting with a 5W rather than 0W, it will have better film strength, at the expense of poorer flow at stupid-low temperatures (like -20F). Your owners manual gives the temperature ranges for 5W40 vs 0W40. Of course, track use over-rides that ( and they now say so, in the new "driving on a racing circuit" manual supplement, included with the GT cars,yea!)
So, for most of us i would suggest FS 5W40 if available. Both Edge 0W40 and 5W40 also meet A40 and ACEA A3.
Happy confusing oil changes,
Grant
Grant
gee-lenahan-at-gee-mail-dot-com