After a two week soak, I checked on it. Clean! I rubbed it down with a SOS pad while rinsing under the faucet, it was looking pretty good. A nice older Wagner. Since the unloved skillet had been to the pool it was time for the heat sauna treatment. In the oven she went. I season at a high temp, and being cheap I use the other old standby Crisco. Between you and me I can't see spending more money on some fancy foo-foo oil that costs more than the dang skillet did. So I seasoned it one time with the Crisco. And here is that old nasty skillet after some time at Dwayne's Cast Iron Spa & Sauna.
I'm posting this to let newer ones know how easy/cheap this process can be. I started with a can of Easy-Off and a black plastic trash bag. You don't need much. And who doesn't have a can of Crisco and a cotton rag laying around? Now I have a free blue plastic chemical barrel, with a lid, from a pool company, that has lye water in it. I drop the item in and let it work, no muss, no fuss. So go try it.