[Ghostt]

I did my own using muriatic acid, I purchased at Lowe's, but you must be extremely careful, of the vapors, and acid itself, and then neutralize afterwards.

Another method is to buy POR15 KIT, that will contain everything you'll need including the coating so you won't have anymore rust issues, but if done improperly the coating flakes off.

Third option, and one I personally recommend is to find a radiator shop, most of them offer the cleaning, and coating service at reasonable prices, and it's professionally done, so no worries.