Here is a test we did with Saferestore, a great product it really removed the rust off windows that had not been cleaned in years. There are a few other saferestore video tests we did there as well.
YouTube - DoITinADay's Channel
Saferestore is a great product. The company I work for, www.buddingco.com has it available. It has been a popular seller due to is green friendly nature. To my knowledge we have some of the lowest prices on it too.