My new-to-me 1987 325e (manual with optional lsd) with 50,000 miles was parked for 15 years 'til 15 months ago (November 2019). The gentleman who revived it from storage did so 100% by the book, draining, flushing and lubricating prior to moving it and turning it over. Runs like thoroughbred. Unfortunately the rear end, likely the differential, groans. It is most noticeable during low speed turns. The car is immaculate; it was previously owned by an aficionado who certainly didn't track it or do anything unusually adventurous with this car. Could it be that in a tiny % of cases the LSD wears prematurely (basically bad luck) in these cars, and my 325e happens to fall into that very small minority?