The method that usually never fails for me is to heat the rusted parts till their cherry red. Cherry red is usually hot enough to burn off the oxidation.

The two penetrants that I've used are Mr Gibbs oil;

http://getgibbs.com/testimonials.php

and Kroil by Kano Labs;

http://www.kanolabs.com/

I don't have a preference between the two, either one seems to work better than PB blaster or,,,,,,

Larry

Ignorance can be fixed Stupidity is forever