I dont like chemical rust converters. I am afraid that if they dont work that the rust will come back. I do aviation sheetmetal structural repair for a living. Any corrosive pits in the metal left behind will allow more corrosion to continue to form. That thought process follows me thru into automotive sheetmetal. I either cutout, spotblast, or chemically remove all the corrosion then repair the damaged area.
I have actually used a 9 parts water, to 1 part animal feed molasses on steel parts to strip off corrosion. It stinks to high heaven, and sometimes takes a week being submerged to strip off the rust, but its cheaper than evaporust. I keep it in a covered vat behind my shop, and wear heavy duty rubber gloves, because it will make your hands stink. Some stuff like bolts and clip nuts the molasses water mixture will eat up, but sheetmetal valve covers, pulleys, fender shields and stuff like that, its the bomb. Works on steel parts thru a process called chelation.