I just bought me a #12 DO.and wanting to season it and i have read on here that flax oil is the way to go so I hope this is the right stuff
Outside is the only way I do it,using the side burner and the grill gets it done nicely.
I now only use flaxseed oil on my CI, it works great. The process does create a bit of smoke and odor, I think it best to do it outdoors or open all of the doors and windows.
good article here
http://sherylcanter.com/wordpress/2010/01/a-science-based-technique-for-seasoning-cast-iron/