Those will come clean. What I did when I had a rusty one was first try to wash with steel wool. Then I dried it obviously and then threw in my oven on the self clean setting to burn off any of the current scuz and seasoning. Then washed and dried again with steel wool and then soap and water to get it as clean as possible and remove any remaining rust (I only had light surface rust). Once dried nicely I started my seasoning process all over again and came out fantastic!