Is it necessary to paint motor?

In the process of prepping the motor to repaint it, I think I stripped almost all the old coating (with the help of paint stripper and the dremel). But now I really like the motor in it's stripped state and don't want to paint it. It has a nice "patina" to it actually



Is it really necessary to actually paint the motor? If I leave it unpainted, would it be enough to spray it down every so often with some kind of lubricant (like WD40)? Thanks.