Following up on the lanolin comment
, I've used Fluid Film as a spray rust preservative when storing motorcycles.
http://www.fluid-film.com/
Another compound I'm told can be used as a release coating for painted surfaces is spray cooking oil. Apparently, spraying cooking pan release spray on your historically appropriately painted vehicles keeps the dirt and grime from sticking to the paint and thereby degrading it. The spray washes off with water and won't harm the pigments. (Just repeating something I heard or read, haven't proved it myself.)