Diesel's retail-wholesale margin is near its widest in a month at $1.30 a gallon

Diesel at the pump is $5.967 a gallon today, the very top of its 30-day range, and the gap between what stations pay wholesale and charge retail is $1.30 a gallon. So the fuel costs more to buy, but the room in it is wider too. For a jobber or a c-store selling diesel, the margin on a gallon right now is about as wide as it has been in 30 days, and that is worth pricing against before it moves. Diesel retail has also climbed 13.5% in 30 days, the biggest move of any pump price on the board.

Crude is what drove it up. WTI is $99.21, up 19.1% over the past month, and is near the top of its own range, at the 90 percent mark. Brent is $104.24, up 17.1%. Wholesale diesel followed, with ULSD futures at $4.807, up 11.7%. Gasoline moved far less. It is $4.295, up 3.7%, at the 81 percent mark of its range, so the strain this month landed on diesel far more than on gasoline. For refiners the month ran the other way. The 3:2:1 crack spread is 55.89, down 9.4 from 30 days ago, so crude climbed faster than the products and squeezed the refining margin even as the retail margin on diesel opened up.

Crude is the one to watch. At the 90 percent mark of its range, it could pull wholesale diesel higher in the days ahead, which may close some of that $1.30 retail gap back up.