flyinlowe

Is the pan rusty, greasy/grimey, or both? If it is just cooking grease and grime I would get a can of EZ Off oven cleaner (yellow lid with lye). Hose the piece down and stick it in a trash bag. Depending on how much grime there is it might take a few days or up to a week. Make sure it stays wet with EZ off and spray it again every couple days if needed.

I use water and stainless steel scrubbers to clean them after the lye soak. The scrubbers are the balls of steel that look almost like a wad of metal shavings. They make them in stainless and brass, use the stainless. While scrubbing the piece turn your oven on to about 230 (or however low it will go). When rinsing and scrubbing I use cold water at the end as the piece will not flash rust as bad. Once it is as dry as you can get it with paper towels stick it in the oven for 5-10 minutes. It will likely have some very slight flash rust on it when it comes out of the oven, don't worry about that. Turn the oven up to 350. I use Pam cooking spray and spray a light coat over then entire piece. Then I use clean paper towels and start wiping it off. All it takes in the beginning is a VERY THIN layer of oil to season so wipe it until it looks dry, trust me there will still be oil there. Once you have wiped it down good pop it in the oven for about 15 minutes. I then remove them and again wipe them down with the same paper towels you used to wipe of the oil the first time. This will help even the oil out as you will likely see some discolored spots where it was uneven. Then back into the oven for 1 hour at which time I turn the oven up to 400, then after 1/2 hour turn it up to 450. After 1/2 hour turn it off and let it cool in the oven. I do all my cast iron that way and then start using it. If you use too much oil it will pool and get sticky or it will also get a zebra stripe look to it.

If the piece you have is newer and has a rough surface and not a smooth surface like the older stuff you can use a plain cotton T shirt to dry it and do the oiling. The rough surface will get paper towel lint all over it.