Volvo: 96 850 Crankcase Ventilation problem?, crankcase ventilation, flame trap

Question
One of the people I do work for on their vehicles called me last night about his 96 Volvo 850 and wants me to work on it. Since I'm not all that familiar with Volvo's I don't know what I'm getting myself into and need to see if this is something I want to do or not. The problem is that the check engine light is on and he tells me that as he drives down the highway at 65 to 70 MPH the car will sometimes intermittently misses and then it quickly goes away and doesn't do it again for several more miles. Also he said that he had  a smog check performed and it passed with the exception of the check engine light being on. He was also told by someone that the crankcase ventilation system was plugged up hence the reason oil comes out of the dipstick tube. They told him in order to service this system the intake manifold must be removed and the system cleaned out and some $60 part replaced. Does any of this make sense and any of it actually true? I believe the car has well over 100,000 miles on it and I don't know if it is a turbo or non-turbo model. Is the diagnostic system on this year OBD 1 or 2?

Answer
John,
You will need to read the codes and see what they are. I would guess they are mis-fire codes, but they could be something else. Once you know what they are you can make the needed repairs.
Yes if the vent system is clogged it will blow oil out the dip stick and eventually blow out engine seals. To replace the breather box the intake manifold needs to be removed. If you first try to replace the flame trap to see if that will stop the oil leakage, that is located in the intake hose at the throttle housing. If you have one on hand you will see the fitting in the hose. A quarter turn c/c will remove it. If the car is a turbo it will not have the flame trap in the intake hose, just the breather box under the manifold. 96 is OBD 2.