Diesel is near its monthly high while gasoline is near its monthly low

Diesel and gasoline are pulling apart. Pump diesel is 5.454 a gallon, up 6.2 percent over the past 30 days and sitting at the 91 percent mark of its monthly range. RBOB gasoline is 3.047, down 10.8 percent over the same stretch and back near the bottom of its range at the 29 percent mark. So the two products your customers buy are moving opposite directions, and diesel is the one costing more at the rack.

The wholesale futures back that up. ULSD diesel futures are 4.385, up 5.7 percent and near the top of their range at 93 percent. The higher cost is coming through your supplier at the wholesale level. What has not moved is your diesel street margin. The retail-wholesale diesel spread is 1.017 a gallon, up two-tenths of a cent over 30 days. In plain terms, you are paying more for diesel and passing almost all of it straight through. The higher pump price is not fattening the margin, it is just a bigger number on both sides of the ticket.

For the refiners the picture is tighter. The 3:2:1 crack spread is 59.64, down 7.22 over the past month. The gap between crude and the finished product is narrowing, which is the gasoline weakness showing up in the numbers. Cheap gasoline pulls the whole crack down even while diesel holds firm.

Diesel could keep leading as long as the futures stay pinned near the top of their range, and if gasoline keeps sliding the crack spread may tighten further into the fall.