So the m52 has this thing called a CCV (oil seperator),
In the m52 motor, there is a very apparent hose that connects to the top right of the valve cover. On the m52 this is a plumbers sealed hose that goes into the CCV. The CCV then, is connected directly at the top to the intake manifold and has another hose going down to the m52 dipstick.
In the m50 motor, there is that exact same apparent hose that connects to the top right of the valve cover with a clip style seal. However. This hose has, right before it connects into the valve cover, another small hose that connects into it. This small hose connects right where the ICV hooks up to the m50 manifold. The main hose, which in the m52 goes into the CCV, goes instead in the m50 to the throttle body, right before the valve (pretty sure)
In essence then in the m50, the blow back oil going through the hose from the valve cover is taken into the intake and combusted. Thus burning some oil. And the vacuum that powers this comes from the small hose that is essentially connected to the manifold.
In the m52, instead of the blow back oil being sent to the throttle body, it is instead separated in the CCV and sent to the m52 dipstick. The vacuum that powers this comes from the CCV being directed connected to the manifold.
Anyway, I plan to have install my old m50s intake manifold onto the m52. After all the DIYs and kits, I thought that couldn't I just use my m50 valve cover or do what this guy did http://www.m3forum.net/m3forum/showthread.php?t=130494
(number 9) but instead have the dipstick plugged and the hose leading to the throttle body. Basically the setup of the m50.
Advantages/disadvantages with blow back oil being burned or returned to dipstick un seperated? Probably less cleaning of ICV and throttle body going the above links way?