Basket Case – With U.S. Refiners Already Running Hard, Relief on Diesel Remains Elusive

A $100/bbl diesel crack spread is an incredibly strong market signal, but it doesn’t translate to higher refinery output because most U.S. refiners already operate at or near their practical limits. As global supply disruptions drain inventories and foreign buyers pull more barrels from the U.S., diesel prices have surged even as domestic refinery runs remain near historic highs. In today’s RBN blog, we look at why high crack spreads don’t necessarily increase a refinery’s output, how market disruptions elsewhere can drain U.S. inventories, and the indicators that will help tell us whether the diesel squeeze is easing (or worsening).

As we noted in Part 1 of this mini-series, 2026 will be remembered by some as the year that diesel cracks topped the century mark ($100/bbl) for the first time. On August 17, the U.S. Gulf Coast diesel crack spread (vs. WTI Cushing) surpassed that sky-high level. On Monday, September 1, 2026, the diesel crack closed at $103.29/bbl, the highest close on record, before reaching a record high intraday price the following day of $108.02/bbl. As of publication, the diesel crack soared even higher, closing at a new record high of $107.72/bbl on September 10. It’s important to note that global crude markets are not terribly short of crude in the traditional sense (despite various geopolitically driven constraints). Instead, the world is struggling to refine enough crude oil into middle distillates to satisfy demand. U.S. distillate stocks in August were on track for their lowest end-of-month level since April 2005 and were the lowest for the month since 1951.

A crack spread measures the difference between the value of refined products and the crude oil used to produce them. A $100/bbl headline diesel crack (the right end of the orange line, measured against the left axis in Figure 1 below) does not mean a refinery earns $100/bbl in net profit.

First and foremost, U.S. refiners and importers currently incur approximately $15 in RVO/RIN compliance costs for every barrel of diesel sold domestically. That cost is passed through 100% into the domestic diesel price. The headline crack therefore includes the full RVO/RIN cost—an amount the refinery must spend on compliance rather than retain as margin. To calculate the effective crack spread, the entire RVO/RIN cost per barrel of diesel must be deducted:

Effective diesel crack = Headline diesel crack − RVO/RIN cost per barrel of diesel.

Thus, a $100/bbl headline crack less than a $15/bbl RVO/RIN cost yields an $85/bbl effective crack (still a historical high value), before operating costs and other expenses. The same distinction explains why, on a comparable basis, U.S. diesel exports to Latin America typically sell at a discount to domestic diesel equal to the RVO/RIN cost: exported barrels do not carry that domestic compliance obligation.

In addition, refiners still have operating expenses, transportation costs, financing costs, hedging effects and the economics of the other products produced by the refinery. Instead, it means that the market value of diesel relative to crude has become extraordinarily high. If crude (blue line and left axis) is expensive because the world is short of barrels, crude prices should be doing most of the work. But when diesel prices (green dashed line and right axis) rise dramatically relative to crude, the problem is further downstream.