I may have done a dumb thing.

I have removed all paint and primer down to bear steel on my fenders. I am not ready to paint yet and want to know what is the best thing to do to prevent surface rust caused mainly by humidity. The fenders are inside and not exposed to elements.

I do not know what type and brand of paint I will eventually choose so I don't want to prime them now and have to remove it later.

Any suggestions?????? What about a periodic spaying of light oil like WD-40? Would that be about as easy to clean off when ready to paint?