After you clean it with Dawn, brushes, the putty knife, and a rinse, let it dry. Then. spray a little at a time with brake kleen and wipe it down immediately with CLEAN rags or old t-shirts. Then paint it.
Here is what I found on the internet:
Rustproofing
Bob Steele of Pete's Crazy Custom Jeeps in Quebec says, "I have a solution to the rust problem. Paint is fine but it will never stop the rust from inside. Here’s what you do -- scrape off as much dirt, mud, rust scale, and loose paint as you can. 1 gallon of general purpose grease, 1 pint of STP (it's like molasses), 1 quart of motor oil (new or used, you could use a gear oil but there is a smell that lasts for quite a while), mix in a metal container, heat it up to a liquid state with a torch or plumber's torch. (Do this OUTDOORS only, BE CAREFUL WITH FIRE AND OILS, Don't Use Your Wife's Oven, and Don't Use Your Gas BBQ). Then spray with a texture spray gun inside and outside the frame and do the whole tub underneath. It's thick enough warm that it won't drip much.
"Don't do this in your driveway and don't park it in the driveway for a week or so until it has settled. In a hot climate it may drip off some residue but it will stop dripping eventually. You can help it settle faster by driving down a dusty road. And this can be done on a new frame or on an older frame where the oils will reach places that paint won't, and absorb into the corrosion and stop the process. Just once will extend the life of your Jeep, or do this procedure every 4 to 5 years like I did. My 86 CJ is still in great shape and solid, my YJs which I bought in 2003 needed major frame and tub repairs. It may sound messy but it’s the only thing that works for sure!"
Mike Cougler, MSgt, USAF Retired, '72-93 [SIGPIC][/SIGPIC]
'67 M725, VIN 10030, Delivery: 7/67
Rochester, NY