Long story short, I daily my 89 240DL including winter (-20~-30C out side). It is b230f auto, somewhere 360000km, engine compression almost 180psi all across, regular maintenance all up to date.
I putted a catch can in-line with the stock PCV system just to reduce the amount of oil getting inside the intake tube. So today I open the can to empty it out, whole bunch of water came out and inside the can its almost like peanut butter, and almost full.
Car runs fine, doesn't really loose oil (some leaks externally), coolant level is fine and clean.

So I took all the lines apart, pretty much the entire PCV system has these oil/water mixture in it, but only a little in the intake tube and throttle body. And the funny part is, when I took the hose off the PCV box, there are clear water coming out of that hose and inside the PCV box, there are also some milky goo.
The top of the engine is supper clean tho, nothing in the oil cap or on the cam as far as I can see. Oil dipstick also fine, it just reads oil, and oil level doesn't go up (at least visually)

So here is the part I don't really get:
1. I know it would condense some water but would it really be this much? the catch can is only there 3 months.
2. Should I just remove the catch can and let the PCV directly suck everything back in and burn them? Or using a catch can to pre-condense it helps?
3. The cold catch can might be the reason for extra condensation, but why would there be condensation in the PCV box? To me that area should be plenty enough hot to evaporate moisture.
4. Drive it long trips might help but to what extent? when it's -30C outside seems it will take a very long time to boil everything off, Sometimes I got home after an 20min drive, the intake manifold is just warm, not even hot.
5. My biggest worry now is there are more unseen condensation inside the engine which can make things go really ugly, is there any way to know without draining all the oil?

Anyone had similar experience before?

Thanks in advance! Happy holiday!

 

Water is a byproduct of combustion and on super cold days more of it is likely to condense as it is recirculating. This could be your problem; I do find that in my 2013 Jetta, there is more "milk" under the oil cap and on the dipstick in the winter than during the summer.
My (then) 740 and (now) 940 are not driven as winter cars so I can't offer them as a reference.
I would empty it out, and then check it regularly. In some ways, it is helping to solve your problem by catching the condensed water prior to being drawn into the manifold again.

 

Thanks for the reply.

I ended up remove it, shorten the PCV hose and run it close to the engine, no more milk shake. The catch can do catches water but some of the water condensed inside the rubber hose and flow back to the crank case, so I figured better let the engine burn them off.

Cheers!