多疵一舉

There is a science behind it: filter design for >30-40 microns, most normal engine wear are much smaller (not harm the engine). Magnetic only catch much larger metal wear(let's say 500 microns). Even in race car, no one will put magnetic near the filter. You may mount on slow oil flow place (like place near oil drain). But metal even thick. At lease, we may hope to help the filter not against it.