Smoking oil and cooking oil are different. The butane method extracts the oils naturally occuring in the weed then evaporates leaving only weed oil.. High % of THC and you can smoke it.

Cooking oil or butter are used to extract the THC from the weed so you can cook with it. You just heat up the oil/butter and throw some weed in there. Then filter out the solids. Its still mostly cooking oil or butter though, you can't (at least I won't) smoke it.
stonefly Reviewed by stonefly on . Extracting Oil Hello all. Long time smoker, first time poster. I'm just starting to grow a couple of plants, and I'd like to share some of what I've been told, and you guys can tell me if I'm out to lunch. a) Oil can come from all the "left over parts". All the leaves, stems, etc. Sure, you can get it from the buds as well, but that's kind of a waste, unless you have that much to spare. b) All cooking, in a nutshell, is using weed oil (as opposed to some other extract or part of the plant). c) Rating: 5