Included with my '32 Coupe are several pieces of sheetmetal, presumably repro parts. There's a RF fender, pair of running boards, a floor pan for the rumble seat area, and the shroud that goes beneath the radiator and wraps around the front inside of the springs, plus a spare tire "well" or pocket that goes in a front fender. This is all bare, unpainted steel, and I have no immediate plans to install the stuff.
How best to protect it? I'm thinking of spraying it with a light-weight oil of some sort. (ATF?, motor oil?) Everything will be stored inside, but not in a heated area. This protection might have to last 10 or more years.