4.8isX5 – Good point on knowing the engine history, at least we now know all the gremlins, and have had all the work done by the same guy.

cn90 – Thanks for the links, the DIY certainly was illuminating, but outside my scope. I will definitely look into the home mechanic!

upallnight – Interesting insight on the lease practice. I will have to double check but it looked like oil changes were done at 3,000 mile intervals, or very close to that.

trader4 – I saw one rebuilt engine on Ebay that comes with water pump, all gaskets, and a thermostat. What else would be routinely replaced/needed when swapping an engine?

Motorsport1207 - I am starting to lean towards that option of the $2,500 home mechanic, but am wary of no business insurance or warranty on work (making assumptions here).

Before I purchased I actually took the car to two different mechanics for a PPO, both indy’s, and one of them was a BMW specialist/former service center guy. Nobody saw the smoke! When we took it to emissions testing it plumed smoke, very inopportune timing, but didn’t happen again for a while. Honestly we don’t get much smoke at all, maybe every other month or so.

Right now the problem is that after a spark plug gets fouled she starts running very rough when idling or at low speed, otherwise I wouldn’t worry about. From my research before purchase it just seems like this vehicle is prone to leaking oil, which I can live with. We also went in knowing this car is expensive to maintain and figured that into the budget, just didn’t know how much valve stem seals cost at the time!

Question:
If we keep the car and do the valve stems, what else should be replaced at that time for longevity/ease of access since the engine is torn apart?

Thanks again for all the help and insights, I know I will make a better informed decision because of all of you!