I have to clean the whole air intake system every 6 months or less because it's clogged with oil residues that are spitted from the flame trap that's right on top on the throttle valve, the valve itself has to be carefully cleaned every time the idle goes bad, it runs very well after I clean the whole thing, including the flame trap and hoses.
Why would Volvo put this oil vapors exit on top of the air intake with no foam filter at all like many other cars have, could I just buy a piece of foam for another car's air filter and put it inside the flame trap capsule? there could be some restriction but I would keep the air intake system much cleaner.
I am using synthetic oil now and it's better than regular oil, it was much worse before but it's still a problem.

Makes no sense. I would not put the foam thing in there. If the foam clogs then you are building a lot of pressure in the crankcase and old weak seal can be blown out. Maybe the air filter is the problem. If you don't have enough air intake it may be socking to much fumes from the crankcase. 92/960 is an oily machine. most of the oil will acumulate at the bottom of the manifold. I would not pay to much attention. Keep running.

I don't know if you are running a synthetic motor oil, but I have found that if everything else in the engine and flame trap system are in good order, the lower volatility of synthetic oils helps keep the vapors to a minimum.

DEWFPO
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1998 S90 077,400 and 1995 964 154,100

There should not be that much oil, how many miles are on the car? You could have a blocked seperator, a black plastic box under the intake manifold, up front, under the altenator, it is attached to the side of the block. It is the end of the one hose for the flame trap. That may be your source of air blockage.

If that is not it, I would do a compression test, you could just have a lot of blow-by, more than the system was designed to handle.

DanR '94 964 338,000 miles (104,000 on the new engine)
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DanR

My car has 132,000 miles in its ribs and in good shape in general, the breather is not clogged, I've done the tests and it blows fine the oil cap, I removed it two years ago and cleaned it with solvents inside, don't think it's bad.
I was thinking of putting a piece of white foam as a filter for those dirty vapors coming out, inside the flame trap, just a thin slice of foam will prevent heavy stuff going into the air intake.

no amount of care and regular maintenance can ever over come the inherent weakness in a bad design of which the 960 is a prime example.

take a tip from a great american poet, robert frost......"Take care to sell your horse before he dies. The art of life is passing losses on.

from “The Ingenuities of Debt” by Robert Frost