Between the huge increase in heavy oil coming in from Canada and the new wave of shale oil production in the U.S., American oil refiners have access to a huge amount of cheap feedstock, which means great margins and powerhouse performances for investors. So many refiners had an incredible year in 2012, and in this video, Motley Fool energy analysts Joel South and Taylor Muckerman tell us that the ride isn't over. Joel gives us some of the top performers over the past year in this space and discusses whether investors can expect these ideal conditions to continue.