The Stovebolt Site Forums The Shop Area Paint and Body Shop AD cab corners and rust.

I have used a product called LPS 3 for many years with excellent results.
It appears to be similiar to the Waxoyl described in the other post.
It will displace moisture and forms a waxy film on the surface.
I find it readily available at most local parts stores at a reasonable cost.
What I have always liked about it is it is thin enough to seep into the tight corners and the hem flanges,and is available in an aerosol form with a straw to reach into tight places,like the corners of doors, etc.
Google LPS3 and check it out.