The acids ‘dissolve’ the rust (iron oxide). The ‘rust reformer’ chemicals do something else chemically (I don’t really understand that process). I think of diesel oil as being more of a lubricant, although, as a fuel it does contain some solvents.
But I hate the smell, especially in my basement, where I often work on chains.
Something surprising that I ran into were seized chains (and bar nose sprockets) that were not rusted, but bound up by dried up grease. I used 3-In-One oil, and some mechanical persuasion, to loosed these up. A diesel soak would probably work there too.
I did an extended test with a diesel/ATF ‘cure’ in an earlier post in this thread. After a number of months the rusted, seized chain remained seized.
Philbert