Opinions on motor oil certainly are like, and can bring out, *******s. But I've never heard a horror story about rotella. Its good stuff for German motors of this vintage. Dino, 15/40, good formula. I ran a couple changes of Penzoil 10w40 that the PO had been using through my 89 300te with unknown mileage (250k+). And while I need to do valve seals, and will probably be pulling the head to check things out, I noticed a difference when I went to rotella. Less leakage, quieter operation at idle/warm and the pressure seems more stable.

Anyone familiar with BMWs will know the M20/M30 engines. The bmw comrades of the M103. Robust, simple, older than humans and truck-like mpg. Know scores of guys in that scene using it. I had a motor from an 88 3 series that I tore down, had machined and rebuilt top/bottom and stroked. Engine had ~200k on it when this happened. Sold the car, but I saw it with the head off for boost a few weeks ago. New owner has the mileage on it up to ~350k. Kept using Rotella and the engine looks good for what it puts up with.