rust

I have lived in Germany for three years and like many places farther North, they use road salt to excess in order to prevent icy roads. Been digging around for some good options in order to prevent and in some cases treat some small rust that's built up. What have you used and was it worth it?

I ran the JKU through the car wash yesterday and realized just how bad my door hinges were getting pelted by gravel on the back roads. Mudflaps are out of the question. What other options are there for protecting the hinges. I've thought about Plasti Dipping them, but wasn't sure if that would...