I have the same problem. 04 X5 4.4. My friend has the same vehicle, same problem. His smokes on startup, mine doesn't. Both have 78K. Replaced CCVs in mine 1K ago, still have alot of oil in the tubes that go from the CCV to the intake , is that normal? I put my finger in the tube, when I pulled it out there was a thick film of oil on it. I have been told my an experienced mechanic that has dealt with this problem before that it is not the valve stem seals but sludge under the valve covers and possibly the oil drainback ports clogged. I have heard of success with Liqui-moly to clean up the engine followed by Auto Rx. I have been told by the local BMW dealer here that if you have a 4.4 that really does have bad valve stem seals that they can be relaced with out pulling the heads and that the parts are less than 200.00. Most of the charge that places are quoting is labor. I've heard of pricing that would give a person a stroke...pulling heads, pulling engine, replacing engine! I've got a better one, if you're going to have to put 10k in a vehicle you paid 15k for used then why not put "No Smoke in it and drive it till it quits?
I love the vehicle, its a sweet ride and I think with some experienced help I can get it fixed without selling the farm! I am actively working on the problem, when I find out what the problem is i will post it so hopefully it will help other people having the same problems. I realize problems can vary from vehicle to vehicle and that one solution does not fix all but I have read many threads that exactly describe my problem. Any experienced help would be appreciated! Thanks!