Oil smoke at high RPM (N52)

[greezy_goblin]

So I was having an issue where smoke would come out of the exhaust at high RPM on my N52, so I figured I'd add my solution here for anyone else who had this issue
The issue would occur when I was above around 3500 RPM (can vary). Smoke would billow from the exhaust, and the engine would shudder a bit. After "purging" this by purposefully doing so a few times (using manual mode for low gear so as not to blind anyone on the road) it would return to normal. It also seemed that the longer I left the car not running,(weeks) the worse it would get, at lower RPM, and I was afraid to "purge" it, since it would not go away after a few attempts. Since the issue would cease after repeating it a few times I figured it wasn't the head gasket or anything "mechanical". The first thing I did was order a new oil separator, which sits on the back left of the valve cover, and has a small vent. I replaced it, but the old membrane did not have any tears. I also replaced the CCV breather hose that goes to the bottom of the intake from the back of the valve cover, but the old one also seemed in fair condition. After removing the intake though, (not necessary, you can put a tube through the throttle body to suck it out Instead)I found a pool of oil sitting at the bottom. My theory is that oil from the crankcase passed through the valve cover (either by the breather hose and or oil separator) and was dumped into the intake, and was pooling, then getting sucked into the combustion chamber when air was rushing into the engine, picking up the oil at the bottom. I think this may be due to using too heavy of an oil, (I run 5W40 and am at 130k miles) and when I drained the oil from the intake, the issue was gone. Expect the issue to come back if you don't switch to a lighter oil (according to my hypothesis). So, this may be the issue if: it only occurs at high RPM, does not persist after "purging" and you are using a heavier oil. I hope this helps, let me know if you have any questions!