The formula is simply 1.8*UGA - USO. I chose this formula because it correctly seems to show times when the crack spread has gone negative. The important aspect of the chart is not to show you the actual crack spread, but to show you the relative relation and direction of the crack spread.
I would not be a bull of refiners here since they have already rallied with the crack spread. TSO, WNR and others have doubled from the bottom! In fact, it could be topping out soon.
