• U.S. diesel refining margins surged above $106 per barrel, a record high.
  • Diesel inventories are at record seasonal lows, and retail prices are near $5.63 per gallon.
  • The squeeze stems from Middle East conflict, Russian supply disruptions, and strong exports.

Diesel's Perfect Storm

The U.S. diesel market is in the throes of an acute refined-fuel squeeze, with refining margins—or crack spreads—soaring to unprecedented levels. The premium of ultra-low-sulfur diesel futures over West Texas Intermediate crude leapt to a record $102.20 per barrel on August 17, and has since extended beyond $106 intraday. That's vastly above the typical $20–$30 range, signaling an acute shortage of diesel and other distillates.

The root causes are multifaceted. Disruptions in the Strait of Hormuz, a conduit for roughly 20% of global seaborne oil, have severely impaired shipping, while Ukrainian attacks on Russian refineries have knocked out significant capacity. Russia, the world's second-largest diesel exporter, extended its export ban through September 30, tightening global supplies further. In response, international buyers have turned to U.S. refiners, driving exports to 1.79 million barrels per day even as domestic inventories have plunged.

According to the Energy Information Administration, U.S. distillate inventories—which include diesel and heating oil—fell by 2.2 million barrels in the week ended August 21, to 103.4 million barrels, the lowest level on record for that point in the year and roughly 14% below the five-year seasonal average. Refiners are already running at 97.4% capacity, but output of about 5.1 million barrels per day hasn't been enough to rebuild stocks.

The result: The national average for on-highway diesel reached $5.652 per gallon, nearly $1.94 above a year ago, and close to the all-time high of $5.81 set in June 2022. In California, prices average $7.04 a gallon.

"Diesel is the lifeblood of the U.S. economy," said Tom Kloza, global head of energy analysis at Oil Price Information Service. "This is going to hit everything from food prices to construction costs."

The margin spike is particularly worrisome because diesel isn't just a household expense—it fuels trucks, farm equipment, construction machinery, rail, and marine vessels, and it's used for heating in some regions. As freight costs rise, they ripple through supply chains, pushing up consumer prices. Indeed, the July CPI was already at 3.4% year-over-year, and higher diesel prices could keep inflation sticky.

Global Ripples

The supply shock is entwined with the Iran conflict and escalating U.S.–Iran economic pressure. U.S. officials say they can sustain a naval blockade, while Iran has blacklisted 45 tankers and threatened conditions on Hormuz transit. Iran and Oman have discussed a temporary shipping corridor, but traffic remains far below normal.

For import-dependent nations in Europe and Asia, this means competing for a smaller pool of diesel. Sanctions compliance has become a legal minefield for shipowners, insurers, and banks, adding to costs. The U.S.–China dynamic is also strained, as Beijing criticizes the pressure campaign.

"The geopolitical risk premium is now embedded in every barrel of diesel," said Amrita Sen, co-founder of Energy Aspects. "Until the Strait of Hormuz is fully open, we're in a precarious situation."

Winners and Losers

The pain is unevenly distributed. Farmers face peak harvest-season fuel costs, squeezing margins at a time when they need combines and tractors running. Large trucking firms can pass costs via fuel surcharges, but smaller operators may struggle. Consumers will see higher prices for groceries and goods. Refiners, on the other hand, stand to benefit from record cracks, provided they can maximize diesel output.

"We're seeing a classic supply-demand imbalance," said John Auers, executive vice president at Turner, Mason & Company. "The refiners that can run hard and optimize for diesel are going to have a very good quarter."

Outlook

The near-term path depends on whether Hormuz reopens and Russian output recovers. If not, diesel prices could climb further, especially as winter heating demand approaches. Goldman Sachs (GS) has forecast structurally higher diesel margins in 2027—around $63 per barrel in the U.S. and $49 in Europe—suggesting the market tightness may persist.

"We're in uncharted territory," Kloza said. "The market is very fragile right now, and any further disruption could send prices to record highs."

Correction: An earlier version of this article cited a headline figure of $106 per barrel for the diesel crack spread; the record close on August 17 was $102.20, with $106 reached intraday. Clarification: Diesel margins are the premium of diesel futures over crude oil, not the absolute price of diesel.