I went thru this last year looking for something to deal with the rust on my truck frame. It seems that products that worked five/ten years ago don't work as well or even don't work at all now.
Loctite Extend worked good ten years ago but on my truck it only took a couple of days and the rust was coming thru again. I pestered the Loctite rep but all he could do was suggest I return the stuff to where I bought it. He said he talked with head office about my issue with the product but got nowhere.
I've heard the same story for POR-15, I read lots of reports from ten years ago where it work well but recent reports not so good.
The LocTite on very light rust seems to be okay but if the rust is that light why not sandblast the rust out and paint it properly.
IMO if you want the rust gone you need to cut it out and do it right, I don't see any shortcuts working.
Here's the link to my adventure with rust. If I had to do it again I'd find a frame in better condition than the one I have but they are very hard to find.
I'm working on a rusty truck frame and am wondering if anyone has any experience with "Rust Converters" These products are supposed to neutralize rust and stop it from spreading. For every video/review that praises a product just as many call the product crap. Do any of these products actually...
canadianhobbymetalworkers.com
Good luck.