they will always rust if you get water on it, and let it sit…
the “coating” which your thinking of a rotor has which prevents it… is only when it is in the warehouse & storage. that actual layer actually should be removed via. brakecleaner when installing them and wiped down with a clean rag. if not, it can cause the brake pads to glaze.
i have not seen a rotor that will not have a coat of rust on it after being used, then having water sprayed on it (washing the car/rain) then letting it sit for a day or two…
screw it, go find some old school endless rotors… :drool: