hello99: It is put on at 400 degrees. And it is always food grade oil. I think this is different from the aluminum foil pans- people in the food forums talk about which pig fat or olive oil, or butter, they personally use.
The company I bought claims to use a vegetable oil, and sometime in the past, even advertised that it was OU certified oil- but that is no longer the case.
Here are seasoning instructions: http://www.lodgemfg.com/use-care-seasoned-cast-iron.asp#3
And here are the FAQs: http://www.lodgemfg.com/use-care-help.asp#5