OK, I had to get in on this. As a long time scout I have dealt with a lot of CI. Boys rarely if ever clean correctly and often abuse the CI. To clean up rusted or heavily coated CI simply boil the CI in tomato juice. It takes a while but it leaves a nice finish. Its done when the rust is gone. surface light rust can be gone in as little as an hour. The longest I have ever boiled a badly treated one is about eight hours using two separate solutions of tomato juice. To season coconut oil is best, flax and linseed go rancid. If you need to "wash" the CI use hot water and salt. Never use a wire brush, bamboo scourers work well for the stuborn stuff. Always season after washing. If you use soap or washing powder your food will taste oh so good the next time.....