Rust 911 or Evapo-Rust and Stuck Pistons

[Tom Wesenberg]

Has anyone tried any of the rust removal products to free up a stuck piston?

[Big hammer]

I have used evaporust on small parts,
on zenith carb it penetrates some what, just enough to loosen screws. After removal rust can be seen in the threads. It works best with high temperatures 80-90*