I was wondering the same thing, recycling oil, but just my house waste oil, not big batches of McD's fry oil.
Was curious about the leftover food waste in oil? Does it effect outcome of final product? Or it doesn't matter, there's still plenty oil left to stick, oil's main job in JWA?
If vegan, should be okay, maybe more beneficial with organic matter for plants? But, if meat is added would we have to wait for putrification before use? And what about dairy, same as meat? Or just filter it?