This is maybe the dumbest, mundanest Poe's Law situation I've ever seen.
Super critical CO2 dissolved polar molecules such as oil and wax, and deposit them somewhere else when the CO2 goes through the phase change back to gas. This is useful in cleaning in the same way that soap/detergent is used to allow water to break up and remove oils on clothes, tools or dishes. In this case the CO2 can be recycled and used again through heat/pressure bringing it back to a supercritical phase.
The oils could be used for other purposes, I just chose fuel as most individuals won't be interested in eating recycled oils from their dirty dishes, and the usage of waste oils for biodiesel, etc. is a better alternative than petrochemicals.