Yeah, been thee, done that. 300SE with 3.45 diffy.
I think what causes it, at high revs, the upper head area floods with oil that cannot drain away fast enough. The oil covers the intake valve seals, and is pulled past the lOUSY OEM SEALS into the engine. I suffered the same highway oil usage from when mine was new until I replaced the valve seals at 100k. Instantly fixed. Of course, the dealer always told me it was normal oil usage.

And maybe it was normal; we rented a brand new '87 300E in
Germany; drove it on the autobahn at 3500-4000 (and beyond, HeHe).
It ate 4 quarts during our vacation (at $7 per). I had Hertz reimburse me.

DG