Diesel's retail-wholesale spread is near its widest in a month at $1.456 a gallon

The gap between what diesel sells for on the street and what it costs you wholesale is 1.456 now, up 0.133 over the past 30 days. That is about 13 cents a gallon of extra room on every gallon compared with a month ago, and it is money sitting in the margin if your retail price has not chased the drop.

Most of that widening comes from the wholesale side easing. ULSD diesel futures are 4.672, down 7.6% over 30 days, and they are at the 70 percent mark of their range, so there is still room below. Retail prices move slower than futures, so when the cost side falls like this the street margin opens up until pump prices catch down. Refiners are not getting the same break. The 3:2:1 crack spread is 54.6, down 14.68 over the past 30 days, which is a real squeeze on refining margin even while the retail gap grows.

Gasoline tells the same wholesale story. RBOB is 3.102, down 12.1% over 30 days, and at the 35 percent mark of its range, closer to the floor than the ceiling. So the softness is on both barrels at the rack, not diesel alone.

The thing to watch is crude. Brent is 108.14, up 4.1% over 30 days, and it is at the 95 percent mark of its range, about as high as it has been all month. If Brent holds up there, wholesale diesel could firm back up and close some of this 13-cent gap, so the wide margin may not last. Natural gas is its own picture if you burn it or watch storage: Henry Hub is 3.162, up 8.6%, and storage is 3567, at the very top of its range. For now, if you sell diesel, the room is there today.