WTI hit the top of its 30-day range at $103.07 as the crack spread tightened $11.67

WTI crude is $103.07, the top of its 30-day range and up 25.1 percent in a month. Brent did the same, $108.14 and up 22.2 percent, also at the ceiling of its range. Crude has been the whole story for the past 30 days.

Refining margins narrowed while that happened. The 3:2:1 crack spread is $55.05 a barrel, down $11.67 over 30 days. Crude ran up 25.1 percent while ULSD futures rose 12.9 percent, about half as fast. When the barrel costs more and the product priced off it lags, the gap between them closes. That narrower spread is the refiner keeping less on each barrel.

For the street, the read is better. U.S. retail diesel is $5.967 a gallon, at the top of its own range, but the retail-wholesale spread widened to $1.30, up $0.233 over 30 days. Pump prices climbed faster than what the retailer paid at the rack, so the margin on each gallon sold is wider than it was a month ago. A hauler or c-store operator is paying more to fill, and the retailer is keeping a bit more of it.

Natural gas stayed quiet next to all this. Henry Hub is $2.899, up 6.1 percent and only 37 percent of the way up its range, so the pressure is all in the oil complex, not gas.

If crude holds near this ceiling, product prices could keep catching up to it, which may widen the crack back out over the coming weeks.