[gobblerman]

I have seen the magnets in the oil drain plug. In fact my 88 4runner came from the factory with one as does my suzuki ATV. Also seen them in the manual trans drain plugs and differential plugs. Don't know it it mattered but I always felt better seeing what was trapped on the drain plug magnet. I would be worried about placing one in the filter though. Ceramic magnets are rather brittle and I suppose could fracture of course the would be caught in the filter.