As we bought DinoEvo in Japan it had absolute no rust. Not a single spot. Quite unusual for a 15+ year old vehicle, but I guess the previous owner didn’t use the van that much as well as kept it inside a garage most of the time. I’m pretty sure this van had never seen snow and salt either.
To keep it this way and protect the undercarriage when we travel, I wanted to apply some sort of rust prevention. I’m not a fan of the common black tar spray as it covers everything underneath with a thick heavy coat. That makes it hard to see rust right from the start when it’s still easy to treat as well as harder to work on any of the covered parts.
Therefore I used a large bucket of Fluid Film*.
Fluid Film is formulated from specially processed wool-wax, highly refined petroleum oils and selected agents to provide corrosion control, penetration, metal wetting and water displacement. These long lasting products contain no solvents, will not dry out and will penetrate to the base of all metals, providing corrosion protection from both natural and industrial atmospheres.
It was easy to apply with a air gun, even inside the subframe and tight areas. It probably will last for a couple years till you need to apply another coat. Another side effect of the product: DinoEvo smells pretty good now :)