Diesel's retail-wholesale spread is $1.627 a gallon, up 52 cents in a month

The gap between what a jobber pays wholesale and what diesel sells for at retail is now $1.627 a gallon. That is $0.523 a gallon wider than it was 30 days ago. If you buy a load and resell it, your street margin on diesel is near the widest it has been in a month.

The pump number backs this up. U.S. diesel is $6.382 a gallon, up 14.0 percent over the past 30 days, and it is at the 95 percent mark of its 30-day range (low $3.459, high $6.529). So retail climbed hard, and it climbed faster than wholesale, which is what opened the spread. Part of the reason is on the supply side: refinery crude runs are 16.257 million barrels a day, down 7.1 percent over 30 days and at only the 31 percent mark of their range. Less product coming out of the plants can keep wholesale diesel bid up and the barrel tight. The 3:2:1 crack spread is $64.65 a barrel, up $3.20, which says refiners are getting paid well to run what they can.

Gasoline is in the same spot, $4.603 a gallon and at the 99 percent mark of its range (low $2.907, high $4.628), so there is almost no room left at the top on that side either. Both fuels are priced near the ceiling of where they have traded this month, and the diesel margin is the piece an operator can act on today.

Watch the refinery runs. Runs this low usually do not hold for long, and if plants bring capacity back the wholesale side could ease and pull that $1.627 spread back in, so the margin you have right now may not be there in a couple of weeks.