I think (hope) that I'm pretty close to having this X5 sorted out. Since the last update, I have changed the oil in both diffs and the transfer case (Red Line 75W-90 gear oil and D4 ATF, respectively).

I have also changed the automatic transmission fluid and filter. On colder mornings, I noticed a slight slipping in 1st gear when pulling away from a stop. It would go away after a few minutes - by the time I got out of my neighborhood. But needless to say, it had to be addressed. The old ATF was nasty - most likely the factory fill. Changing the fluid cured the slipping and also noticeably smoothed out the shifting.

I had the MID display rebuilt. Now I can see what station is on and what time it is! One of my past E39s also had a ton of dead pixels in the MID and I bought the kit to fix it myself. The kit was about $60 and after several attempts, I could not get all the pixels back. In fact, the more I tried the worse it got. I ended just up buying a used MID with a good display to replace it. Instead of taking the chance of blowing another 60 bucks and still having to replace the MID, I just sucked it up and paid someone to do it. It cost $100 for the rebuild, which is a tad pricey to me. But it works perfectly, so I suppose it was worth it.

I had to put a set of tires on it almost right away because the ones on it had cords showing. Ever since then, there had been an annoying vibration in the steering wheel. I came across another set of wheels/tires on Craigslist for $100! I swapped them out and the vibration was gone. So it was definitely in the tires (and not the suspension, as I feared). I took the original set back and had them rebalanced - vibration cured! An easy fix, for once!

Replacing the upper control arms in the rear suspension cured a very loud and very irritating squeak. The outer ball joints were completely rotten and binding badly.

I still haven't been able to find the problem with the O2 sensors, though. I did some troubleshooting and it looks like maybe the post-cat sensors are the problem, even though the error code says it's all 4. None of the obvious stuff is the problem (broken wire, blown fuse, etc), so I might just replace the sensors and hope for the best. They do not look OEM, so maybe that will take care of it. If not, at least it'll be one less variable to deal with!

I am happy to report, though, that it passed its first torture test. I had to drive up to Atlanta (a 2 hour ride for me), and then get from one side of town to the other on the Friday after New Years day. One part of the trip was a 5 mile drive that took over a half hour. Then, on the way home there was a 20-mile traffic jam on I-75. No problems whatsoever on the trip. Yay.

And finally:


Better?