No I have not invested directly in oil co's but that could be an interesting hedge against the cost of fuel. All you need is the cash. But if I had that kind of serious cash I would have a much bigger fuel problem because I would own a killer sportsfishermen.
(That said, I have done well in russian funds that invest in mostly oil in the last decade though, (TRF and LETRX) But I am not going to sell them to buy gas at the pump.)