Been a long time since i did some car frame work. After I sandblasted the frame, i painted it with POR15 and then painted over that. You can get a small kit for $30 on Amazon. I just saw the rust holes on it and you can scuff and paint it, but will it bubble again? POR15 is a rust preventive coating, rock solid hard when it dries. Seems to be just like that Tremclad but POR15 is has more steps in the kit to use, then just paint. Might be overkill, but thought i would through that out there. Sounds like the Tremclad is going to be one shot and done.