I just replaced the hose leading from the oil trap to the flame trap because it inadvertantly broke during some routine maintenance as I was cleaning the trap. Yes, the oil trap can be cleaned, dealerships (who do things by the book) will suggest you replace it. I suppose of money is not an issue, replacing it would be easier. It is not a welded assembly (plastic if it's like any other Volvo oil traps) and easily removed after removing the intake manifold. Before removing the intake manifold which is both time consuming and "disruptive" to the engine, why not just remove the hose leading to the flame trap and confirm that it is clear of debris. Yes, over time, but a considerable amount of time and mileage, the oil trap will indeed clog up. My 850 has over 200,000km on it and all I do is clean the flame trap every six months and have recently replaced the hose. What makes you think the oil trap is plugged? BTW, contrary to popular belief, the manifold does NOT have to be removed to replace the hose previously mentioned. A trick using a long screw driver to guide the hose onto the oil trap was shown to me by my independent Volvo technician.