The Trading Economics Crack Spread index, a measure of the margin between crude oil and refined products, reached a record $75 per barrel in September 2026. The level represents a near 200% increase from mid-February, before the United States escalated threats of strikes on Iran. The resulting conflict brought naval blockades that halted crude exports from Gulf Cooperation Council countries through the Persian Gulf, restricting refinery feedstock for major oil-importing nations. U.S. refiners responded by operating above 100% of nameplate capacity, while domestic gasoline and diesel prices surged. The presidential administration considered banning diesel exports, but crack spreads remained at record highs as pressure on diesel consumption from U.S. refineries clouded the outlook for gasoline production. Limited flexibility among Gulf and West Coast refineries to shift toward gasoline could lead to lower crude-processing volumes.