I've been using electrolosis for some time now on small parts - up to approximately 15 gallon capacity. I have found that if the part has rust, grease, and paint on it, and you want all three removed, sodium hydroxide (lye) is your best bet. $10/gallon at walmart or home depot. Sold as septic main line cleaner in the plumbing section.
However, this one may increase your toxicity a bit. Wear gloves, apron, and goggles. And keep your mouth shut!
