JFP - I hadn't logged in in 4 days after checking later in the day for your response. My apologies that I apparently seem "suspicious" in my lack of immediate response.
Your data looks solid and shows a fairly ridiculous level of shearing in the period of time shown. The TBN retention is misleading - TBN tends to decrease drastically immediately, and then settle in.
Nonetheless, it's troubling. I've seen M1 0w40 shear down to a 20 grade plenty of times, and not affect notable engine life, but that was after an extended run. I think its known to shear down to a 20 grade in the DI Audi/VW 2.0t engine, but that engine even eats up redline 5w40 in 5k miles.
I'm sorry to say that after 20 minutes of googling, I can't find a single boxster 2.5 liter UOA to gain any personal insight on beyond what you've shared. So I'll take your words as wisdom until I find either further reinforcing evidence or something to dispute it.
Don't know if you care, but here's my own relevant history of UOAs:
Mobil One 15w50 in my 2008 Subaru Legacy GT (known for eating up oils) -
Link to 15w50 UOA
60k miles of extended duration UOAs on my '06 Civic SI, up to its current usage of M1 0w40 for 13k:
06 Civic SI UOA series
I'm going to step out in a few minutes and, as a result of your UOAs, will buy either redline 5w40 (if I can find it) or M1 5w40 TDT instead of using my stock of 0w40.
I appreciate the time you've put into sharing this - I am not a blind shill to either side and though I'd prefer to see your data set, I also know you have a solid reputation here.
Thanks for taking the time to respond to me in depth.
Threaded Mode
