In the following video, Fool.com energy contributors Tyler Crowe and Aimee Duffy discuss what this earnings season shows us about the continuing boom in the American oil-refining industry. Tyler goes into what the earnings reports for Valero Energy (VLO -0.06%) and Marathon Petroleum (MPC 0.21%) looked like and highlights how both companies were able to exceed expectations based on the continuing glut of available cheap crude, and he tells us what he's going to be looking for to get a clearer picture of where the industry as a whole is heading.