Ha ha, I just bought a set to do the gas filler door, I think that if the magnet will stick to the drain plug you should be good. I would be concerned with it transferring to oil pan or as TerryD stated sticking to other internals. Once they stick they are usually set. In my experience with the filler door, they are so powerful just getting on edge they tend to go off on their own. As long as it does not transfer when pulling plug you should be fine. I am concerned with my gas door I might not be able to open it