This has been an excellent discussion, and I would guess we've all learned a lot. I'd like to add one more note: Be sure to avoid getting gasoline at a station when the tanker truck is filling the station's underground tanks. When the station tanks are being filled, the gunk in the bottom of the tanks is stirred up, and if you're drawing your gasoline at the same time, you're likely to wind up with some of the gunk in your automobile tank. It happened to me ONCE. Never again. Happy motoring, everybody.