Petroleum is a nonrenewable resource, so there is no sustainable oil company. A green lifestyle certainly does not include frequent trips to the pump. But when you do have to fill up, don’t pull into any station. Though it may be a “lesser of all evils” game, some oil companies are more worthy of your dollars than others.
Organisations like the Sierra Club have developed criteria to rank the major players. Big Oil is one of the least transparent industries on the planet, but you can get information on pollution released from refineries, environmental disasters (not only spills but destruction of habitat and communities for pipeline), and whether a company has an exit strategy (some actually acknowledge climate change and support alternative energy).
-Abrams, “365 Ways To Save The Earth”, 2008