I think this a good product, and believe I've seen a picture of a cut apart oil filter they have where there are lines of metal particles on the inside of the filter opposite of where the magnets were placed. I would wonder about the validity of these on a modern engine where many of the parts are made of aluminum. Maybe some of our more knowledgeable members like Joe Black and Tone have firsthand experience with these though. I want to say Joe Black also did a few posts about the magnetic drain plugs, or a quick oil drain plug or something.