My family and I have made a concerted effort to buy gasoline from anyone EXCEPT Mobil and Exxon. We received an email that said those are the 2 biggest oil companies in the states (duhhhh) and if millions of people just went to any other dealer, they'd be forced to drop their price. I wish I had faith in the public to do so, but I'm not so sure about that, but I'm going for it. I'm definitely going out of my way to use these other stations and if I plan ahead and make a point to fill up when I'm by them, who knows, it may work.
Hopeful!
Looks like the internet keeps some fantasies alive, as it seems like the message you received is a variation on this oldie-but-goodie:
http://www.snopes.com/politics/gasoline/nogas.asp
It won't matter. But I suspect you knew that. At least I hope you already knew that. B)
If everyone in the USA tries to avoid ExxonMobil for even just a day, and simply buys their gas elsewhere, those other stations will quickly run out of product, and many would likely raise their prices when they see hordes of drivers descend on their station.
It's hard for consumers to manipulate multi-hundred billion dollar markets. Good luck with that.