Since the X5 has 8 expensive CV boots that can possibly tear I decided to spray all the rubber boots with lube approx 3 yrs ago. No scientific data to support my findings but the boots look like there holding up well and dont apear worn. It takes less then 2 minutes to get 6 out of 8 boots. Just cut the wheel all the way to the left and right and spray. No jacking/crawling needed. The last two boots are in the rear in the center of the truck and require you to get underneath. Since the rear do not stretch from turing - there's much less incidents of tears.

As for the lube, I'm not a big fan of WD40 or silicone. Instead I use CRC 656 or Seadoo Lube (leftover from my jetskis). Boeing makes a good spray called T-9 as well. I typically spray all the rubber parts before the winter and after an oil change.

You be the judge, 2002 X5 with 20's:





After a bath and enjoying the sun