from my experience with different products, EVAPO RUST is the stuff to use. for a 5 gallon pail its about $99-115 depending where you buy it. a definite pro of this product is that its safe for the environment as well and can be disposed of easily. works on all metals and does not affect paint either. once parts are submersed in the solution just check up on it every 1-2 hours or if its badly rusty, let it sit for a few days. It has not damaged one part yet.