1. What Iran has offered, and what the offer is not
The offer runs like this: the strait reopens within seven days if the United States first states officially that it wants a diplomatic solution, second eases military pressure, and third lifts the blockade of Iranian ports; a timeline would then be agreed (senior Iranian official to Reuters, 22 September 2026, via Israel Hayom). It was conveyed through mediators, and Washington is reviewing it. Iran's delegation to the UN General Assembly, meeting in New York this week, has been authorised to re-establish contact with the mediating countries.
What it is not is an agreement, and the record counsels caution. After the failed Islamabad talks the United States imposed a naval blockade in April; a memorandum signed on 17/18 June promised to reopen the strait and end the blockade; from 8 July the ceasefire collapsed after alleged Iranian attacks on merchant ships and the blockade was reinstated (Wikipedia, 2026 Strait of Hormuz campaign). Anyone acting on the seven-day offer today is acting on a statement of intent.
2. What actually flows through Hormuz today
The strait is not shut, but it is a bottleneck under US control: about 10 million barrels a day pass through (US Energy Secretary Chris Wright, 13 September), and the past two weeks carried more crude, cargo and LNG than at any point in the past six months; Iran itself exports zero barrels, and the primary lanes have been cleared of mines (Admiral Brad Cooper, CENTCOM, video message of 20 September 2026, Business Standard citing Bloomberg). Before the war the strait handled about 125 large commercial vessels a day (Israel Hayom) and roughly a fifth of global oil and LNG trade (EnergyNow). The difference is what the world market has replaced since March through stock draws, pipelines and higher US exports.
The pipelines are the second bottleneck. Saudi Arabia's East-West pipeline, which together with the UAE bypass carried around 5 million extra barrels a day past Hormuz in the second quarter (Fortune/McKinsey, 17 September), was knocked out by drone attacks on 13 September and restarted at the weekend at a low rate; restoring the old 4 million barrels a day will take six to eight weeks (OilPrice.com, 22 September). On Sunday Aramco loaded about 14 million barrels onto seven supertankers (EnergyNow). The EIA's outlook of 9 September assumes production shut-ins of 6.7 million barrels a day in August and constraints persisting into the second quarter of 2027 (EIA STEO). Our glossary entry on the Strait of Hormuz explains why the waterway matters this much.
3. Three scenarios for crude, diesel, heating oil and gas
Scenario 1, the reopening happens and holds: crude reacts first and hardest. When deal reports circulated on 12 June, Brent dropped 3.37 per cent in a day to $87.33 (Yahoo Finance); Goldman Sachs put the effect of a one-month-earlier normalisation at roughly $10 a barrel for late 2026 and $5 for 2027 (Yahoo Finance, 21 June). The EIA's base path already assumes a decline to $90.66 in the fourth quarter of 2026 and $73.74 on average in 2027 (STEO, 9 September). Diesel and heating oil follow more slowly: US distillate stocks are at their lowest September level since 1982 (EnergyNow), Russia keeps its export ban until the end of October (Hydrocarbon Processing), and the freight premium of at least 25 per cent of the crude price to Asia (OilPrice.com) only unwinds once tankers sail reliably again. Gas moves with oil: the TTF fell 3.5 per cent to €70.66 on 22 September (finanzen.at), because a reopening would bring Qatari LNG back.
Scenario 2, the talks drag on: prices stay where they are and every headline moves them by two to three dollars a day, as between 18 and 22 September ($104.33, $101.61, $99.97; Fortune, our API). For heating oil that means a high price without direction: $6.53 a gallon for US diesel (AAA), €167.51 per 100 litres in Germany on 22 September (HeizOel24), €1,855 per 1,000 litres in France (prixfioul.fr).
Scenario 3, the offer fails as it did in July: the market returns to the September highs. Brent was above $107 on 16 September and at $118.35 on 31 March (Wikipedia). Diesel, not crude, would be the driver in that case, because stocks are empty and refineries have been running flat out for months. Which scenario plays out will be decided in New York and Tehran, not on the exchange; our page Oil price today keeps the daily reading.
4. What to do now, and what not to do
Do not buy or sell on headlines. If you need heating oil and your tank is below a third, order: scenario 3 costs more than scenario 1 saves in its first weeks, heating oil follows crude with a lag of days, and dealers pass declines on more slowly than rises (see pass-through effect). Above two thirds you can wait out the seven-day window; by 29 September you will know more. The full rule with all thresholds is on Heating oil: buy now or wait?.
For diesel users the relief is slower whatever happens, for the reasons in our page on the diesel shortage of winter 2026/27. For gas customers in Europe the question is whether the reopening comes before winter: German storage stood at 56.8 per cent on 22 September (AGSI), details on gas storage and winter 2026/27. The broader status of the crisis is on our Hormuz crisis hub.
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