Hey Mr. Green,
If you had to recommend a particular brand of gasoline, which would be "best"? Because BP emphasizes "beyond petroleum" and was the first oil company to stop lobbying to drill the Arctic National Wildlife Refuge, I've been filling up only at BP-Arco stations. But with its recent pipeline leak in Alaska, I'm having second thoughts. — Helmuth in San Jose, California

Deciding where to buy gas is about as tricky as waltzing with Dick Cheney on his favorite oil slick. Different oil companies are responsible to varying degrees for different woes. (To name a few: polluting air and water, destroying wilderness, poisoning indigenous people's land, promoting denial of global warming, exploiting workers, and even collaborating with oppressive governments that don't give a dipstick about human rights or environmental protections.)

Further complicating the matter, most oil companies actually do some good things for the planet, such as supporting conservation groups or developing alternative energy sources. But all things considered--and despite its pipeline fiasco--BP-Arco is still your "best" choice, along with Philadelphia-based Sunoco. To see how Sierra ranks the eight biggest oil companies, visit sierraclub.org/sierra/pickyourpoison.