Whatever 'miracle' product you use, the best it can do is slow down the process. The only way to do the job properly is the cut the rot out and replace with new metal.
I have used Dinitrol RC800 in the past on my 2CV. It seemed to seal the surface reasonably OK so I could paint over it. But it still came through again within about 2 years. That was better than just painting over the rust though!