I have the same car with 50,000 miles on it. I was also concerned about the 10,000 miles oil change intervals, but thought I'd give it a try. I lasted until about 9500 miles and just had to change it. But to make myself feel better, I also had an oil analysis done. Turns out the analysis of the synthetic oil at 9500 miles was better than the analyses of other cars I've done with half the mileage using dino oil. I'm sort of convinced.

But I would recommend you look to see if the transmission has been serviced or replaced.

Len
'99 E300TD