Why the Iran War Created a Global Refining Crisis, Not Just an Oil Shock

The Iran war has exposed a bottleneck between crude production and the fuels people actually use. Since the conflict began on February 28, attacks on energy infrastructure and the effective closure of the Strait of Hormuz have disrupted not only crude exports but also the refining, shipping and inventory systems that deliver diesel, gasoline, jet fuel and LPG.

That is why a retreat in benchmark crude prices does not necessarily mean cheaper fuel at the pump or lower transport costs. The binding constraint has shifted from crude alone to the conversion and movement of refined products.

Crude is only the starting point

A barrel of crude is not directly usable in most cars, trucks, aircraft or heating systems. It must reach a refinery, be processed into specific products and then be transported to the market where it is needed.

The war has disrupted each stage:

• Refineries have lost access to feedstock or suffered damage. The IEA reported that Middle East and feedstock-constrained Asian refineries cut runs by around 6 million barrels per day in April.
• The main export route is unreliable. Oil and product flows through Hormuz fell from around 20 million barrels per day before the conflict to an average of 2.7 million barrels per day during March, April and May.
• Alternative routes and rerouting cannot replace normal trade immediately. Gulf exports recovered in June, but total Gulf oil exports, including bypass volumes, were still 16.1 million barrels per day—well below the pre-war average of 24 million barrels per day.
• Inventories are absorbing the shortfall. Once stored products are drawn down, buyers must compete for new cargoes at a time when production and shipping capacity are both constrained.

The result is a shortage of deliverable products rather than a simple shortage of crude in the ground.

Why Brent can fall while diesel and gasoline remain expensive

Crude and refined products are related markets, but they are not interchangeable. Brent reflects the marginal value of crude oil. Diesel and gasoline prices also reflect refinery yields, regional inventories, product specifications, freight, insurance and the availability of vessels.

This creates a counterintuitive market pattern: crude can become cheaper while refined products remain expensive. The IEA’s July assessment described refined-product markets as tight even as increased crude supplies pushed oil prices sharply lower. Global refinery runs rose in June, but remained 6 million barrels per day below the level a year earlier; Middle East export refineries had not restarted, Russian throughputs were curtailed by attacks, and Asian refineries were running at reduced rates.

In other words, cheaper crude does not solve a shortage of refining capacity. If refinery output falls faster than demand, product margins rise even when the crude benchmark retreats.

Hormuz disrupts both refinery inputs and finished fuels

The Strait of Hormuz is usually treated as a crude-oil chokepoint, but its importance is broader. It carries crude, refined products and LPG. A sustained reduction in traffic therefore creates two linked problems: refineries struggle to receive feedstock, and importing markets struggle to receive finished fuel.

The IEA said the strait’s pre-war flows of about 20 million barrels per day had fallen to an average of 2.7 million barrels per day in the first three months of the disruption. Reuters later reported that Iran said the strait would remain closed while negotiations continued, with traffic falling to six vessels from a 10-day average of about 11.

Limited crossings may move individual cargoes, but they do not recreate a dependable supply chain. Tankers, insurers, traders and buyers need predictable access, not merely occasional passage. Higher risk premiums and longer voyages also raise the delivered cost of every cargo that does move.

Russia turns a regional shock into a wider diesel problem

The refining crisis is not confined to the Gulf. Ukrainian attacks forced major central Russian refineries to halt or reduce fuel production. Reuters reported that the affected plants accounted for about 30% of Russia’s gasoline production and roughly 25% of its diesel production.

Moscow responded by restricting exports and turning to imports. Russia introduced a diesel-export ban after refinery attacks triggered domestic shortages and price spikes, while officials said the country would begin importing fuel. Traders later shipped nearly 30,000 metric tons of refined fuel from South Korea to Russia, including diesel and possibly jet fuel, according to shipping data and sources cited by Reuters.

The squeeze reached international markets as Russian seaborne oil-product exports fell by about one-third month on month in July, to around 3.9 million metric tons. Russia then extended its gasoline and diesel export bans through January 31, 2027.

Russia’s reduced availability matters because a major fuel exporter is no longer reliably supplying the regions and traders that normally help balance diesel markets. A refinery outage in one country can therefore increase competition for replacement cargoes elsewhere.

Inventories are the system’s shock absorber

Storage normally smooths temporary mismatches between supply and demand. It can cover a refinery outage, a delayed tanker or a short-lived export restriction. But inventories cannot absorb an extended, multi-region disruption indefinitely.

The IEA’s August outlook forecasts global oil supply down by 4.3 million barrels per day in 2026, with additional losses in the Middle East and Russia only partly offset by growth in the Americas. It also projects a 1.8 million-barrel-per-day market deficit in the third quarter.

Aramco chief executive Amin Nasser said cumulative lost supply since the conflict began had exceeded 2.6 billion barrels and warned that global inventories were running low. Earlier IEA reporting also described global inventories falling by an average of 3.8 million barrels per day during the period covered by its assessment.

The precise inventory figures in public reporting vary by dataset, geography and measurement period. The consistent signal is more important: stocks have been used to cushion the shock, leaving less protection against another outage or a longer closure.

Shipping capacity cannot substitute for refinery capacity

When normal routes become dangerous or unavailable, ships must take longer routes, wait for safer windows or command higher insurance and freight rates. That raises the price of delivered fuel and can reduce the effective availability of vessels even when the global fleet has not physically disappeared.

ADNOC Logistics & Services’ purchase of five very large gas carriers and six very large crude carriers for about $1.3 billion illustrates the strategic value of controlled transport capacity during an unstable market. The deal expands the ability to move crude and gas, but it does not restore damaged refining units or create immediate supplies of diesel and gasoline.

This distinction explains why a shipping response can ease one bottleneck while leaving the central product shortage intact.

Why reopening Hormuz would not end the crisis overnight

Reopening the strait would be an essential first step. It could lower security premiums, release delayed cargoes and restore access to crude and LPG flows. But it would not instantly:

1. repair damaged refineries;
2. replace specialised processing equipment;
3. restore refinery units that were shut down for safety reasons;
4. reverse Russia’s export restrictions; or
5. rebuild inventories depleted during the disruption.

Aramco’s chief executive warned that even if the strait reopened, returning to normal would take time; Reuters reported his estimate that it could take up to 18 months for the system to fully recover. The IEA likewise continues to forecast lower supply while an agreement enabling the reopening of Hormuz and unhindered transit through the Bab el-Mandeb remains elusive.

Relief would therefore arrive in stages: first through safer shipping and the release of stranded flows, then through higher refinery runs, and finally through the rebuilding of product inventories.

The practical conclusion

Calling the disruption only an oil-price crisis misses the mechanism affecting households and businesses. The war has impaired the system that converts crude into usable fuels and moves those fuels across borders.

The strongest evidence points to four reinforcing constraints:

• reduced refinery throughput;
• restricted movement through Hormuz and other shipping routes;
• lower Russian fuel exports after refinery attacks; and
• shrinking inventories that can no longer absorb repeated shocks.

That combination allows Brent to retreat while diesel, gasoline and other refined products remain expensive. Until refineries are repaired, shipping becomes dependable and stocks are rebuilt, the global energy market will remain vulnerable even if crude production begins to recover.