I purchased my Filter-Mag's many years ago and have used them as intended. They have increased significantly in price over the years; I can tell you that when I cut open my filters for a look (mostly curiosity) they do catch ferrous material that sticks to the sidewall of the filter. When you touch the area, it looks and feels more like wear grease/fretting residue. In aviation, electro-magnetic chip detectors are used to provide the aircrew a visual caution light if the particular gearbox has shed enough metal to complete a circuit. The point though is wear begets wear; and yes, "maybe" the filter catches it, but if not, if you amortize your purchase investment over 10-15 years, it is a worthwhile investment if you keep your vehicles long term or purchase brands that use the same diameter filters. We have owned Honda's for 20 or so years so I just move mine to the new vehicle. There are many more sources for high-temperature neodynium/rare earth magnets today than 10-12 years ago. Try a few on your filter, cut your filter open at your change interval and see if the additional expense and work might be worth it to you. In the end, it's an individual choice for your maintenance routine; I felt then and still do feel that it's a good practice.