I've had my pool since 1979. And I am referring to a sand filter. A DE or cartridge filter might be okay since they are easily replaceable. Replacing the sand in a filter tank is a royal pain. But I do know that filters remove only solid, particulate matter from the water. Petroleum-based contaminants are a whole 'nuther ballgame. You might be able to use a coagulant to get the oil to adhere to that to remove it from the water, but, again, I sure would not run oil through a sand filter. And thank you for your expert opinion. It's nice to know someone I can count on for sound advice if I ever need it.