I Feel your Pain.. Mine is a 2006 4.4 that started smoking at 65 thousand miles. At 70 I left a James bond smoke screen. especially when hot and idled for a short time in traffic. Mine did not have oil coming in thru the intake.

After several months of trying everything I gave up and had the valve stem seals replaced. Problem fixed. No oil loss , clean exhaust pipes, car runs better, everything it should have been from the start. Thank you bmw..

One thing to note on your idea of opening the engine vacuum is that the bmw system with the intake system relies on a high engine case vacuum for everything to work properly. So changing this will cause other problems. Had this checked with a special vacuum gage at my local indy that fits on the oil cap. My vacuum was correct. I cannot remember the required level of vacuum only that on the n62 with the special intake was higher than most engines.

Cost to replace valve stems was not cheap but cheaper than the entire valve job. 1700.00. When we examined the old seals they were very hard and the opening was larger on the exhaust than the intake to the point some were oval.