Someone mentioned molasses. I have seen it work though never done it myself. you have to use animal feed grade molasses because you need to have the natual sulfur in it. You mix it 10-1 with water and drop in your part and walk away. The beauty of this method is that it takes the rust and paint off and is not toxic to the environment. After the effect wears off, (probably a dozen or more uses) you can just dump it. Feed molasses is pretty cheap too.
