I have rust on my Pathfinder that came from out of state. Its now in California. I have went under the car and used several wire brushes and sanders to knock most of the rust off, I cleaned it off with brake cleaner and some Rust-oleum rust converter paint over the chassis. Mine just has minor rust, nothing eating through metal.
I just did my CV axles and this found this rust under the grease cap
Cleaned all the parts in added new grease.
Since i was in there I had to paint and clean parts. The yellow cover is for the ABS shield and i painted yellow since i ran out of black lol
Put it all back together and mounted some new rotors as well