Several years ago, when I bought a rust-free 1987 Subaru GL in Arizona and brought it back to the Northeast, I was concerned about how its paper-thin sheetmetal would fare against the scourge of salt that state and municipal transportation authorities order dumped on snow-prone roads each winter. After doing a bit of research, I came up with something that looked like it would ward off salt and moisture from my car's chintzy steel (along with regular washing and keeping a close eye on paint chips and scratches). My secret weapon? An oily rust inhibitor from a Cheektowaga, New York-based company called Carwell.
This is a companion discussion topic for the original entry at https://www.hagerty.com/articles-videos/articles/2017/11/23/the-secret-to-rust-proofing