Bill Tindall
Over time the atom thick coating of zinc that the Chinese put on bolts now days will corrode away and over time the threads will mingle. I suggest you put some anti seize compound on the threads. Any place supplying machine shops will sell it. It consists of metallic particles of copper, maybe molybdenum sulfide and other stuff and I am not sure how it all works. I find it keeps nuts from seizing even outdoors. Or at the very least add a dab of grease.