I was reading this Sport Truck magazine article that was used to support a "Royal Purple" sales pitch. They (see below) brought up the aforementioned point about those Magnetic filter trap deals (BearTrap or FilterMag). I use the Bear Trap. Was using it just for catching metal particles that might be in the oil due to start up wear, etc, just for the sake of engine longevity. But, I didn't consider the idea that the filter magnets might be useful in the event of mechanical failure.
http://www.royalpurple.com/sport_truck/sport_truck.htm"Pay attention now because this next tip will save your engine in the event of a valve train failure. We run a Filtermag on all of our engines because they work. It’s exactly what you think it is: a high powered magnet for your oil filter that will make ferrous metals stick to the walls of the filter instead of trying to pass through the filter media. Should a mechanical failure occur within the engine, like a broken lifter or flattened cam lobe, the Filtermag will keep those pesky metal particles from entering the oil system and ending up in the bearings. Check out the photos if you want proof. Look at all of that metal debris trapped up against the wall of the filter where the Filtermag is positioned — that debris came from a hydraulic roller lifter breaking."
