For light to moderate oxidation naval jelly (you can get it at auto supply stores) is easy to use and works very well. Just be sure to remove any parts you treat, it's not going to be friendly to woods or finishes.
Coca Cola is another matter. I think it's phospheric acid or something like that that goes after so many things. I stopped drinking it when I was a kid after seeing a mechanic walk over to a Coke machine and with one of those little bottles they used to make, totally clean a corroded car battery with it. Soaking chrome or plated parts in Coke can clean it, but it it's there too long it can eat the plateing.
I forgot, there are things that are more heavy duty, probably the best product for serious rust is something called POR 15. It's amazing.