tried PAM on it?
PAM is the spray stuff containing lecithin, which is a "phospho-lipid" meaning it is an oil with phosphate added. It it very good for your skin. It might help the skin of the skillet too, not sure I have not tried it on cast iron. Works great on everything else I have tried it on. It is a super-lubricant with extremely high melting point. For that reason it is great as a cutting tool lubricant as well. I use it instead of shaving cream. Several ladies I know copied this and are now getting marbly-smooth legs without nicks or cuts. The razor lasts longer as well.
Ok, well my latest pan is cast iron, but with a Honey-comb surface. Made by Staub, this pan browns meats perfectly without any sticking at all. It is almost non-stick in operation. Staub designed the surface using a computer, the pans came out around 2007. They are spendy, but worth every penny. They need no seasoning, as the surface is covered with crystaline enamel which gives it a greater surface area and higher searing effects. I am a hobbyist with this, so I do spend money like water on whatever is the next thing, so understand this may not be for everyone else who just wants a nice burger without an arm and leg into it. I paid about 140 total for the 12" Staub Honeycomb cast iron skillet. It's the best searing tool ever devised as far as I can tell. Though cast iron is good, and I have a lot of well-seasoned cast iron, this is a new-era product, almost in a different league. If you love seared meats especially then try to get your hands on a Staub Honey combed cast iron skillet, the larger the better so you can put the onions and things around the meat while it sears. Once done, add a little water and deglaze the pan onto the meat. No need to clean the pan, just wipe with paper towel and store uncovered, leave whatever remains in the pan to add to the flavors next time. If it gets builtup, clean with brush and hot water, no soap.
I use only a bamboo spatula, no metal on the crystalline enamel surface.
cheers,
Bob