Why interfere in Libya?

President Obama surprised me with his military incursion into the civil war in Libya because it was uncharacteristic of his more diplomatic style of international relations. When a new President takes office he is briefed by the CIA and Joint Chiefs on secret American world commitments that the public is unaware of. I suspect that the security and stabilization of the world's oil supply is our responsibility since we are the only military superpower. Most Americans, however, do not consider that a good enough reason to go to war, so Obama says it's to prevent a civilian massacre and Bush said it was because of WMD's and Iraqui freedom. Is oil the real reason for most of our involvement in the Middle East?