I've read a lot about seasoning cast iron over the past few years. Watched youtube videos and what not. Years ago I seasoned a pan, probably with Crisco, and did an hour in the oven @ 450 IIRC
Some months ago I read a thread on a food/cooking/cookware forum with a long discussion about a method a gal posted in a blog on the internet. She used flax seed oil, and did this multiple oven seasoning method. I can't recall how many times in and out of the oven before it was done, but it stimulated some discussion on the forum, it would have totalled up to 14 hours to finally season the pan ! One lady in that discussion made more sense to me than anything I had read. She said her grandmother, and that generation seasoned cast iron by cooking in it.
So when I recently added this #7 slant logo to my battery I recalled that. After I stripped it down with the easy off I took a jar of bacon grease I had collected and swabbed it down. Threw it in the oven @ 250, increased to 350, then to 450. Left it in an hour and then shut the oven off and let it cool down. Since then I've fried a heap of bacon in it and eggs in the bacon grease. Seems to have worked a treat.