The USGC 3-2-1 crack spread (purple line) averaged $71/bbl in September, up 9% from $65/bbl in August and 170% above the $26/bbl averaged in September 2025. Diesel cracks (orange line) led the increase, averaging $104/bbl in September, up 12% from $93/bbl in August and 226% above the $32/bbl averaged in September 2025. Gasoline cracks (blue line) also strengthened, averaging $55/bbl in September, up 6% from $52/bbl in August and 132% above the $24/bbl averaged in September 2025. The gap between diesel and gasoline cracks widened to $49/bbl in September from $41/bbl in August, with stronger diesel margins accounting for nearly two-thirds of the August-to-September increase in the 3-2-1 crack spread.
Refining margins then eased in early October, with the 3-2-1 crack spread averaging $65/bbl through October 5, down 8% from September. Diesel cracks declined 10% to $93/bbl, while gasoline cracks fell 6% to $51/bbl, tightening the diesel-gasoline gap to $42/bbl. Despite the pullback, the overall crack spread remained more than two-and-a-half times its October 2025 average, with diesel cracks remaining well above gasoline cracks.
