Diesel's retail-wholesale spread is $1.336, down over the past month

Your street margin on diesel got thinner even as crude fell apart. The retail-wholesale spread is $1.336 a gallon right now, lower than it was a month ago. Crude dropped far more than your pump price did, and the gap between what you pay for product and what you sell it for closed rather than opened.

The crude side is near the floor. WTI is down 24.1% over 30 days and is at the 1 percent mark of its range, about as low as it has been all month. Brent is down 22.5% and in the same spot. Retail diesel only came off 12.7% and is still at the 55 percent mark of its range, so the pump has passed through less than half of the crude move. Retail fell slower than crude, so your spread tightened instead of widened.

The margin that did widen belongs to the refiners. The 3:2:1 crack spread is 54.91, up 9.94 over the month. When crude falls faster than refined product, the refining crack fattens, and that is what happened here. ULSD futures are down 9.4% and are at the 11 percent mark of their range, so wholesale diesel is cheap in absolute terms even while your cut of the retail dollar shrank. Refiners are catching this drop; the street is not, at least not yet.

If crude holds near this floor and retail keeps grinding down to match, the retail-wholesale spread could recover some of that lost ground in the next couple of weeks, so it may be worth watching your rack-to-retail gap day by day rather than pricing off last month's number.