Your engine relies on its oil for lubrication and cooling. As that oil mixes with metal-to-metal parts it picks up contaminants that can spread and cause excess wear and possible motor failure. Sound scary? It is, which is one reason to change your oil often, and even go an additional step to removing particles from the system that an oil flush might not purge. Andy Smith shared a few reasons on why it's good to use magnets on oil covers and drain bolts as part of your engine maintenance program."Using magnets to catch metal particles in your oil can prevent a lot of failures by getting the particles out. But also, by looking at what's stuck on the magnets, you can get an idea where the metal shavings are coming from to detect any internal wear early. There's likely going to be clutch fiber material because that's the most abused part of the motorcycle. It's just regular wear and tear on the bike. If there's any bright, shiny metal, it could be tranny parts, edges off the gears, etc. If there's any casting, it could be possibly from a shift fork or another cast part. Sometimes you have to try to think of what is in the motor that resembles what you have there in your hand."