I called a local BMW shop which has helped me out before.
They said to place the 0 ring in the recess on the oil pan. Not on the dipstick tube.
There is a grove which the O ring must sit in about an inch down inside the recess.
Grease up the tube and slide it in.
It worked.
If you place the O ring on the tube, it will just push up to the top.
It will not set in the groove and you will leak oil.
I have one more O ring question.
Replacing the oil separator and the hoses was, possibly, the most aggravating job I have ever done on a car!
I am still not sure if one of the hoses has "snapped into place.
It is the hose which goes into the plenum.
The one with the nipple that connects a small hose to the rear (nearer the fire wall) end of the plenum.
The larger part of the hose (with the nipple splitting of on an angle) has an O ring.
Is that O ring supposed to go inside the connector on the plenum or just butt up to it.
No matter how hard I push, I cannot seem to make the "snap" sound or get the O ring inside.
Can anyone help me with this dilemma?
I have quit for the evening and should be able to finish in an hour or so in the morning.