get pan good and warm  put a little oil in not much JUST A FEW DROPS IN .dump some salt in start rubeing it around  with paper towls  will be warm on hand but change paper towl . you will see black come off or rust .let pan cool down but warm.  rince with hot water .set on stove burner on low till it dries .now to make it turn black and not rust use mutten fat from bucther not much get pan good and warm not to hot rub around with fork .let it cool down. dump oil out wipe down .when i find a old cast iron that looks bad that's history were have you been and what have you done .if you have a out side bbq i use that. that if you get it to hot it might flear up if you do it outside you can use the rag that you wiped out the mutten fat on the out side of pan to keep it black . now when all done never seal with lid on leave it off set . NEVER EVER USE SOAP. you will never get soap flaver out/. salt makes a rubing coumpound .IF YOU GET ANY OF THIS STUFF TO HOT IT WILL FLAIR UP. DO IT OUT SIDE IF YOU DO NOT KNOW WHAT YOY ARE DOING OR WILL BURN YOUR HAND.NEVER LET THIS OIL OR FAT GET HOT JUST GOOD AND WARM