Brent crude hits $97.85 as Iran war enters sixth month

Why did oil prices jump to a six-week high?

Brent crude rose 0.9% to $97.85 per barrel Sept. 8, the highest level in about six weeks, as the U.S. war with Iran entered its sixth month. The climb puts crude back near the $98 mark last seen in late July, when the conflict first spiked global oil prices. For small fleets, every dollar of crude movement translates to roughly 2.4 cents per gallon at the diesel pump once refinery margins and distribution costs settle in.

The six-month mark matters because it signals the war is no longer a short-term shock. Fuel surcharges that carriers negotiated in March and April assumed a quick resolution. Those assumptions are now outdated, and fleets running on thin margins are absorbing the difference between what they collect in FSC and what they pay at the pump.

What the $97.85 price means for diesel

Brent crude at $97.85 puts the benchmark roughly $11 above the $86.66 low hit Aug. 26, when sanctions tightened on Iran and traders briefly expected supply relief. That two-week swing alone represents about 26 cents per gallon in potential diesel movement, though retail prices lag crude by one to three weeks depending on regional supply chains.

Diesel futures hit $4.68 per gallon Sept. 2, a post-war high driven by refinery crack spreads that reached a record $102 per barrel in mid-August. If crude holds near $98, refiners have little incentive to compress those margins. The math for a 10-truck fleet running 1,000 miles per week per truck at 6 mpg: every 10-cent diesel increase costs $1,667 per week, or $86,667 annually, before any FSC recovery.

How long the Iran war has kept oil elevated

The conflict began in late March 2026. Brent crude traded in the low $70s before the first strikes. By early April, it had spiked to $89. The six-month duration now exceeds the 1991 Gulf War (43 days of combat) and approaches the length of the 2003 Iraq invasion's initial phase. Longer wars mean sustained risk premiums in oil markets, which means sustained diesel costs for carriers.

U.S. refineries responded by processing 17.4 million barrels per day in mid-August, the highest run rate since 2019, but that output has not brought diesel prices down because crude input costs remain elevated. The Trump administration announced a Venezuela oil deal Sept. 1 intended to cut fuel prices, but volume and timing remain unclear, and the market has not priced in meaningful relief.

What fleets should watch next

Oil volatility has defined the third quarter. Brent traded as low as $86.66 on Aug. 26 and as high as $97.85 on Sept. 8, a $11.19 range in 13 days. That kind of swing makes fuel budgeting nearly impossible for small fleets that lack the hedging tools available to large carriers. Dispatchers should assume diesel will track crude with a one-to-three-week lag and plan fuel stops accordingly.

If the war drags into October, the fourth-quarter diesel price floor will likely sit 40 to 50 cents above pre-war levels, even if crude stabilizes. That gap represents the refinery margin expansion and supply-chain risk premium that has persisted since April. Fleets that locked in fixed fuel surcharges early in the conflict are now underwater. Those negotiating new contracts should index FSC to weekly diesel averages rather than accepting flat cents-per-mile adders that assume stable fuel costs.