Removing Rust Stains from Aluminum Siding

A mobile home that I bought had a horrible rust stain on one part of the skirting; I simply got some of Zessler's I think it is called Bulleyes 1 2 3 or something like that; it is a primer; I put it on the entire skirting and it covered it completely and looked great! I did later paint it with aluminum paint from Lowe's that was recommended. That solved the problem!
Since mine was white, the primer was white, and then the new paint was also white.
Is there any way you can put a drain in to divert the water from coming down in the same spot all the time? and if so, would THAT cover the rust? Most "rust" is not going to go away, and if it is simply discoloration from water going down it, try scrubbing it with a simple solution of sudsy water, with a non abrasive scrubber. If the rust is truly rust, the paint should be gone in that area; and then that is when you will need to primer the area; and then paint over it. Good luck! You will find that Valspar ultra premium paint from Lowe's is made for aluminum; it is thick paint; different from any I have used before. It does cover in one coating, and a gallon goes a very long ways!

Aluminum does not rust. Metal must be something like steel or iron. Perhaps WD-40 will work.