US diesel hits $6.204 a gallon as refining premium rivals crude
The U.S. retail diesel average reached $6.204 a gallon on September 13, according to AAA, a new record. Wholesale prices show how much of the increase comes from the refining premium. S&P Global assessed U.S. Gulf Coast ultra-low-sulfur diesel at a record $5.0125 a gallon on September 10 while the prompt diesel-WTI crack spread reached roughly $102 a barrel, the highest in the series cited by S&P Global.
West Texas Intermediate was also around $102 a barrel. Converted to gallons, a $102.48 crude barrel is about $2.44 per gallon; a $102.19 diesel crack is another $2.43. Together they explain about $4.87 of the $5.01 Gulf Coast wholesale price before local basis, freight and other market differences. Scarcity after the refinery is contributing roughly as much per gallon as the crude itself.
Inventories are falling despite high refinery utilization
The U.S. Energy Information Administration expects domestic distillate inventories to fall below 100 million barrels in September and remain below the 2021-2025 five-year low through the end of 2026 and most of 2027. EIA links the draw to lower Middle Eastern, Russian and Chinese distillate supply and unusually high U.S. net exports.
Normally, a $100-plus crack spread tells refineries to run harder and maximize diesel yield. U.S. plants are already doing much of that. S&P Global reported refinery utilization averaging about 93.5% so far in 2026, above 2025, with some operators deferring maintenance. Yet inventories remain thin because the replacement barrel is valuable abroad as well as at home.
Net exports have been at or near a five-year high in every month since February, according to EIA. High margins encourage U.S. refiners to produce more, but high foreign prices keep drawing that additional supply toward export markets.
Russia adds a second product-specific constraint through refinery disruptions and restrictions on diesel, marine fuel and gasoil exports. A missing diesel cargo cannot be replaced simply by producing another barrel of crude. It requires an operating refinery with the right feedstock, configuration, quality specifications and logistics.
The Saudi pipeline outage adds another layer because it raises the cost and uncertainty of crude and product movements at the same time. But the crack-spread arithmetic shows why an oil-price retreat would not fully cure the diesel problem. If WTI fell $15 a barrel while the diesel crack remained near $102, the crude component would fall by about 36 cents a gallon and the product premium would remain around $2.43.
Freight carriers face record fuel bills
At $6.204 a gallon, diesel is 68% above AAA's year-earlier average of $3.6981. Carriers with rapid fuel-surcharge resets pass much of the move to shippers; spot operators and slower contracts finance the gap first.
The forward path is also different from crude. EIA's baseline assumes tanker traffic normalizes and diesel cracks decline through mid-2027. If Middle East product flows remain constrained or refinery outages persist, crude can soften while the product margin stays historically wide.
With oil around $100, crude accounts for only about half of the prompt wholesale diesel price. Lasting relief also requires the refining premium to fall as refinery output recovers, product trade normalizes and inventories rebuild. A decline in crude alone would leave that large second component in place.
Sources
- AAA national fuel prices: https://gasprices.aaa.com/
- U.S. Energy Information Administration, September 2026 Short-Term Energy Outlook petroleum products: https://www.eia.gov/outlooks/steo/report/petro_prod.php
- S&P Global, record Gulf Coast ULSD and diesel crack spread: https://www.spglobal.com/energy/en/news-research/latest-news/refined-products/091126-platts-assesses-gulf-coast-ulsd-above-5gal-for-first-time
- Associated Press, U.S. diesel above $6: https://apnews.com/article/636252b3b82326b41661ee5c4073dacb