[Freon]

Couple year later update, still pretty sure this thing is 100% snake oil. It catches almost nothing, but perhaps more importantly I don't think it does anything the filter does not. There are only a few contaminants that are magnetic anyway, plenty of non-magnetic metals among other things.

he filter gets both the magnetic and non-magnetic stuff. I just don't see what even finding stuff on the plug proves, probably just stuff the filter would catch anyway.

The magnet is one small spot in the bottom of thee pan, nothing is forced past it. Magnetic force drops off incredibly fast with distance (1/R^3). No matter how strong this this is it will only pull magnetic particles towards in in a very small hemisphere around it.

I wouldn't buy one again unless it was for a small iron engine with no oil filter. I think it's silly, right up there with acupuncture. If I has spent more than a few minutes thinking about the physics and engine operation at play I probably could've save myself $35.