As I mentioned before, conventional filters filter more efficiently (in terms of particle capture) as they get dirty, but at the cost of reduced flow, eventually to the point where the filter has lost its utility.

To some degree, the same thing would happen to a K&N-type filter, but I would be also concerned that a large amount of dust on the filter would absorb much of the oil, and reduce the adhesion properties that the filter depends on. If there is enough oil to wick through and around the captured debris, then I think the filter would continue to operate effectively.

BTW is anybody here old enough to remember the old "oil bath"-type air filters found on some old small engines and even very old cars? It consisted of a pool of oil; incoming air was forced to make a 180 degree turn just above the oil. Much of the particulates in the air would carry forward and land in the oil. Another crude form of inertial impactor...