I hope you have better luck with the storage companies than i have. Last oone i bid was $3.oo a door and they said that was way to much. Needless to say the doors are still dirty.
I believe the product you are referring to is called "Penetrol". It is a product made by the Flood Co. and has been out for years. It is a white milky like liquid that is easily applied by hand or airless sprayer. It acts as a protective coating to guard against corrosion. It is also used as an additive to mixed in oil based paints to help with penetration and flow and eliminate unsightly brush marks.
I use it on my tools and exposed metal parts to prevent rust. Check out http://www.floodco.com