I think they'll probably still work. I imagine lube would affect it more than paint and that's actually marketed as a solution. Some are just for pins while others are sold for every contact point meaning some people just drench their discs in this crap from my understanding. https://www.autozone.com/brake-and-power-steering-fluid-additives/brake-lube Idk, in my experience braking hard a few times cleans off rust on the discs for the most part.