the K&N or any cotton gauze filter are meant for 1:1 cars, not RC of any kind. they will let very small particles through that will sand your piston sleeve down. in 1:1 cars the particles just get flushed into the oil filter and dont do damage. a friend purchased one and now his engine has lost compression, after just a few months. lost enough compression that it runs for a few min then overheats and dies.