Interesting - read this.
The F1 does not have a magnet. Today's oil filters can filter as much as 5 microns with the average probably being 20 microns. 5 microns for instance will filter the white blood cells out of your blood. Because all the engine oil is sent through the filter first any metal that could possibly get through would be microscopic at best. This is why when a magnetic plug is used, mostly only a grey mud like substance is found on the magnet. That mud is all the microscopic harmless metal that is a normal result of fine particles of metal that wear off the rings, cam lobes and cylinders. Anything larger would be trapped in the oil filter. Now these fine particles which are normally harmless are being attracted to this magnet on the drain plug. Now they have been all grouped together and magnetically charged to stick to themselves, and any other steel part in the engine, so effectively microscopic particles are now large pieces again, that can break loose from the magnet and find their way usually to the oil pump pickup screen. Over time the screen becomes clogged and it is blamed on sludge, when in fact it is this clump of metal all reassembled into a grey metallic sludge that sticks to anything metal and won't let go. Starving the oil pump for oil.
Now there is a place for a magnetic drain plug, Motorcycle engines where the engine and transmission share the same oil, where broken gear teeth can become an issue, and on any device where you have an oil sump and no filter, like a manual transmission, and some automatic transmissions. There are also some diesel engines that use engine oil to operate the fuel injectors where even microscopic metallic particles can become an issue. Today's modern gas engines, really do not need them, and this is why most manufacturers do not use them anymore. I hope this helps.
