Yes, that is how it should work. However it is not a passive trap but a pressurized one and a large vacuum source attached so oil when the filter material is saturated will blow by. The saturation point is depended on each engine. Some will be longer, some will be short and so on. Now a separator is different than a filter, its function is to separate and keep the heavy oil at the bottom, not suspended in a filter that has to move air thought it. Its no different than folk that run multiple oil filters, or multiple water separators, etc.

My belief with modern engines is that layering some of the solutions allows you bypass some long term problems. Having dual oil filtration like main oil filter and bypass filter, you keep oil clean and help remove additional soot from the motor oil which keeps the internals ways very clean. CCV multi-filtration/separator on turbo engines helps keep the the turbo and remainder of the intake clean. Running dual water separators and filters helps keep the fuel system clean and less issues with the injectors and pumps.

Just my 2 cents on the subject

Cheers.

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