I'm not sure what "literally oils" means in a chemical sense, but all of the essential oils I've ever interacted with are hydrophobic and form a distinct layer

I'm not sure what "literally oils" means in a chemical sense, but all of the essential oils I've ever interacted with are hydrophobic and form a distinct layer on top of water. I'm not sure but that might be definitional to what an essential oil is. I've actually steam-distilled essential oils before: essentially you push a bunch of steam through plant material and condense it into a funnel that drains from the bottom, so water can flow out and be discarded while the oil remains in the funnel. (It's a pretty fun process IMO, and about as safe as boiling a pot of water). I don't think the human body can process most essential oils for caloric energy: molecularly they look much more like drugs - no long carbon chains.