I have also cleaned and maintain my cast iron with a bit of oil and sea salt. I rub it all over the warm pan, then wipe it out with a paper towel. Water should never touch a cast iron pan. After you use it, you should always season it with oil by rubbing it all over the pan with a soft cloth before you store it. Good luck!
I think it was mentioned above to throw it in the old fire and allow it to stay in that fire while all the gunk burns off. Leave it till morning, then season it again. I have done this to a few of my in-laws hand-me downs and they are like new. So what that means is you need a campfire and some patience a little elbow grease and you will be loving your old pans!