What's best to use to stop rust?

[Owicretci]

I have a rusty tailgate, but other than that my '88 Ford Bronco is in pretty good shape. Even the radiator supports aren't super bad.

There is a whole lot of surface rust all over underneath, though. I was wondering if I could wire-wheel it off and paint it with something to protect it. Is that worth bothering with? If so, what should I use?

[Kaiser]

After wirewheeling give the bottom a nice coat of boiled linseed oil, it penetrates and creeps into every nook and cranny and really adheres to the steel, than you can cover with under body coating if you want. If you just coat with any kind of underbody coating it might not stop the rust, it may look nice but underneath the rot goes on without showing.
One word of caution : lay out all the shoprags and brushes you used with the linseed oil OUTSIDE, don't throw them in a trashcan, they can self combust and destroy your workshop !