What does it take to clean the rust off the undercarriage of a vehicle driven on salted winter roads?
Nothing, unless you are getting the car ready for a show, you just leave it there. It is normal.
Where is it rusting??? The body or frame/suspension??
If Body then I’d get it looked at. If not it WILL rust through. If it’s just frame and suspension then forget about it. Nothing you can do…and it’ll take DECADES for it to rust through those parts.
Especially in areas where they salt the roads in winter, it’s a good idea to periodically take the car through a car wash that sprays the undercarriage. At least this way the salt gets removed regularly and the rusting can slow down.
We’re going to sell it and a few people have been leery of it. We now live in the South where this isn’t a common issue.