I have alot of cast iron pans and a few of them I have puchased very cheap at garage sales and boy did they look nasty, People must of thought I was nuts buying them, Took them home -some I sprayed with oven cleaner first, others i put a wire brush bit in a drill and cleaned it, then brillo pads, sand paper. You can't hurt it. Just reseason it.
I generally will do on my gas grill so it doesn't stink the house up. I have one dish I make that just makes the pan not a easy wipe out. I use brillo pad -soap and water - then I put on a burner and heat it up and then wipe it down with oil on a paper towel or back to the grill -- I have no problems. I also will do the same for my stove top grill --I had a friend thought she was going to have a heart attack when she saw me put one in soapy water once. I proved to her it was fine. The big secret is Reseason !!!! You can't hurt it ITs Cast Iron
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