Drain bolt with magnet. As we know there are all kinds of metal parts inside the motor all the time. In the process of operation they are worn out and metal shavings circulate through the motor together with the oil. Especially many chips in the process of running-in. But this is all theory, in reality a magnet can save your car from a motor wedge. Question for reflection: is it worth spending a small amount of money on a drain bolt with a magnet or then lay out a round sum for repair? I think the answer is obvious, definitely not unnecessary.