Diesel's retail-wholesale spread is 1.28, down 33 cents in 30 days

The diesel retail-wholesale spread is 1.28 today, down 33 cents over the past 30 days. That is a third of a dollar per gallon of street margin gone in a month. If you are pricing a delivered contract this week off last month's margin, you are pricing off a number that no longer exists.

Crude fell faster than the pump

WTI is 71.41, down 20.7% over 30 days, and it is sitting at the 7 percent mark of its 30-day range. Brent is 76.01 and sits similarly low at the 9 percent mark of its range. Retail diesel is 4.578 and is only down 12.1%, still at the 51 percent mark of its own range. The pump has given back a little over half of what crude gave back. Rack prices are falling faster than street prices, and that is what the spread number is showing you. Gasoline shows the same shape, with RBOB down at the 6 percent mark of its range while U.S. retail gasoline at 3.911 is still at 58 percent.

Refiner margins

Refining margins have widened over the same period. The 3:2:1 crack spread is 57.34, wider by 9.72 in 30 days. Cheap crude and firm product prices are a good combination for a refiner, and right now they have both.

Watch the crack

If it stays this wide, refiners have room to keep running hard, and the product supply that follows could push rack prices lower still.