VINEGAR Cleans Heavily Rusted Metal FAST.
This is the cheapest, fastest and easiest way to remove rust or clean off rust. It is nothing but inexpensive white vinegar that you can buy anywhere. This only took a few hours to clean off all the rust. If you have to clean off extremely heavy rust it may take a couple days of soaking the rusty part in a 50% solution of white vinegar and water. It always works to safely remove all the rust, if you let the vinegar work long enough and give it enough time.