Over the past year I have "dangled" a small magnet in the power steering reservior on 4 FWD Volvos. These magnets have all collected a black coating of steel dust, more on the older cars. I wipe it off and it keeps coming, though in smaller amounts. This stuff can't be good for the power steering. I used the magnet core from a cabinet door latch and tied nylon twine thru the hole in the magnet and to the spring on the reservior cap, so that the magnet hangs in the fluid.