I couple weeks ago, I took the jalopy to my favorite dealer for some fluid changes, and promptly sent samples to Blackstone. My 2018 M550 had about 56000 miles at the time.
To simplify, they advised me that the LL-01FE with 8500 miles (yes, I pushed it) was fine and that I could try extending it to 11,000 (which is what the service computer says, too). I don't think I will actually do that since I intend to keep the vehicle in perpetuity.
They said that the transmission fluid and rear diff fluid were good, and recommended changing both of them after another 70-75K miles. (((That rang a bell - the diff in my 1997 540/6 received its Royal Purple nearly 200,000 miles ago. Oops.)))
The front diff fluid was another story- they were concerned and said I should "sample" (change) it after 20K more.
The transfer case fluid got lost in the shuffle but I will be doing that in a few days.
Everything else seems so happy - I wonder what's up with that front diff? Guessing they are not cheap to replace... but I'm guessing it won't actually go TU for a few more years.
Anyway, I hope my experience is helpful to others...
