I've used it on cattle guards and pipe fences, wheels and flatbeds, truck frames and UTVs. But I was looking at my chain rack and thinking I was stupid to let them get rained on. Now I wonder if Ospho would be appropriate on a working chain? Of course, the 4 corners of my load always get gold DOT chains so any LE rolling by can see it easily, but the bucket and ripper get a plain chain, just like when I secure a load under 10k. Ospho turns iron oxide into iron phosphate. But I don't know if that will hold up well in working chain use.
Sounds like a good idea rusty chains are annoying A derusting dip in muratic acid and rattle can cleans them up pretty nice too but them people think they are extra good chains and "borrow" them more often lol