I am sorry it I wasn't clear Dave. If it is just the inside is splotchy then pour in some caustic (careful/caution).
Usually I will fill a milk bottle from the 'soup', bring it inside and do this on the kitchen bench.
You will only need a minimum, maybe 1/2”, or more if you wish or need to. Let it sit, then with gloves and a scourer or rough rag, carefully work the surface until the oil is lifting. Pour out the caustic, wash off with clean, cold water, dry.
Reseason.
I use an oven mitt to remove the hot cast from the oven, sit it in the casserole tray and carefully apply more oil and wipe using tongs.
Then back into the oven at 225+C for another 30-40 minutes. On the final sequence I will often wack the temp up to 270C until the oil stops smoking, then turn off the oven and let it cool down at its own rate.
I use grapeseed oil but not solely.
Whereas Cheryl uses paper towels, I use lint free cloth folded a number of times and a size that suits me and the tongs. If the cloth gets toward saturation as Cheryl pointed out, I set that aside for applying in the next season. Then get another dry one.
There are only a few rules with seasoning and just as there are any number of roads to Rome and you will find your own way too :)
edit: just checked the stove dial and edited temps. Note to self, don't rely on memory ;D
So if just the inside is splotchy(which it is for me) then use the cold water detergent cleaning to remove the inner coat and then season? Heat the items ... apply Crisco and them wipe off(more completely) and heat again.
I was using the seasoning method listed here. Heat to 450 ... take out and when cool enough to handle by hand apply Crisco and put back in oven at 400 for 30 minutes then turn off and let cool in oven.
