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.
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USGC Crack Spread Climbs as Diesel Margins Surge
USGC refining margins strengthened again in August as surging diesel cracks pushed the 3-2-1 crack spread to an average of $65/bbl, more than two-and-a-half times its year-ago level.
Cracking the Code – What 2026’s Record Crack Spreads Tell Us About Refining Economics
Crude oil may get the headlines, but the fuels made from it have delivered some of the market’s biggest surprises of 2026. With supply disruptions, strained trade flows and compliance costs all shaping this year’s numbers, let’s look at what goes into a crack spread and what we can learn from it.
USGC 3-2-1 Crack Spread Cools but Remains Strong
The USGC 3-2-1 crack spread has cooled from its spring highs, but refining margins remain exceptionally strong. June's average crack spread is running more than 100% above year-ago levels, supported by elevated gasoline and diesel cracks.