What has actually happened this week
Oil has been falling since the start of the week. Brent was trading around $95 a barrel on 20 and 21 August. By Tuesday 25 August it was down to roughly $90, and it dipped below $87 during Thursday's session before settling near $88 — a fourth straight session of losses.
The driver is diplomatic rather than economic. Iran and Oman have reached an agreement covering each country's share of the waters of the Strait of Hormuz and the revenues associated with them. Earlier in the week the two sides were reported to be discussing a temporary joint maritime corridor through the strait, with technical talks continuing towards a permanent arrangement that would cover how the strait is administered, how information is shared between the parties, traffic management, and the provision of maritime and security services. Qatar has continued mediating, and Pakistan's army chief travelled to Tehran in support of the process.
Two other things pushed in the same direction. The latest round of US economic measures against Iran turned out to be milder than traders had braced for, with Washington so far stopping short of secondary sanctions on Iran's trading partners. And President Trump said around 10 million barrels of oil passed through the strait on Tuesday, repeating his claim that mines in the waterway have been cleared. Satellite data has also pointed to Saudi Arabia stepping up loadings from terminals inside the Gulf.
The caveat that matters most: None of this means the Strait of Hormuz is reopening. Tehran has explicitly cautioned that restoring the waterway would take more than an agreement with Oman, there is unresolved doubt over whether Washington would accept an arrangement it isn't party to, and reported plans for Russian escalation in Ukraine are keeping energy supply risk firmly on the table. Talks progressing is not the same as shipping flowing.
Meanwhile, at the pump: diesel went up
This is the part that shows why oil headlines and forecourt prices are not the same story. The Government published road fuel price statistics for the week commencing Monday 24 August on 25 August. They show:
- Petrol: 161.63p a litre — down 0.17p on the week. Effectively flat.
- Diesel: 182.82p a litre — up 0.37p on the week.
- The diesel premium: 21.19p a litre, wider than the week before.
So at the exact moment crude was falling, UK diesel was still edging higher. On a 55-litre tank that is roughly £88.90 for petrol and £100.55 for diesel. Diesel drivers are paying about £11.65 more per fill than petrol drivers for the same volume — a gap that was a fraction of that size a year ago.
There is nothing sinister in the direction of travel by itself. Pump prices lag wholesale costs, and wholesale costs lag crude, so a fall that started on Monday could not possibly have reached forecourts by Tuesday. But it does explain why "oil falls" headlines so often feel disconnected from what you actually pay.
So how long does it take to reach the forecourt?
The rough working rule is around two weeks from a sustained wholesale move to a visible change on the average pump price, and sometimes longer on the way down than on the way up. Retailers buy fuel forward, so what is in the tanks under the forecourt today was bought at prices set some time ago.
The word doing the heavy lifting there is sustained. The RAC's consistent position through this year's volatility has been that it takes a lower oil price held over several weeks — not a few days — to bring wholesale fuel costs down meaningfully. Four sessions of falls is a promising start and nothing more. We have already watched this cycle run the other way twice in 2026: crude dropped to around $69 in early July after the US–Iran memorandum of understanding, then spiked as high as $105 on 23 July when attacks on tankers resumed.
Worth keeping in perspective: Even after this week's slide, Brent is up around 7% over the past month and roughly 29% higher than it was a year ago. The US Energy Information Administration's August outlook still assumes disruption of about 0.6 million barrels a day continuing through to the end of next year, with most regional production only returning to pre-conflict levels in early 2027. Its forecast has Brent averaging about $85 through this quarter before easing towards an average of $69 during 2027. This is a market coming off a peak, not one returning to normal.
What a fall would actually be worth
If a sustained lower crude price does feed through, the arithmetic is straightforward. Every 1p a litre off the pump price is worth 55p on a 55-litre tank. So:
- A 5p a litre fall saves about £2.75 per fill.
- A 10p a litre fall saves about £5.50 per fill.
- For someone filling weekly, a sustained 10p reduction is around £286 a year.
And it can move quickly when conditions line up. After the June diplomatic breakthrough, the RAC reported diesel falling by a record 17p a litre across June, with petrol down 8p. That is the upside case, and it is a real one — it happened ten weeks ago.
The real question: will retailers pass it on?
This is where it stops being about oil and starts being about the forecourt you happen to use. Earlier this month the Competition and Markets Authority reported that some retailers had been slow to pass on savings as wholesale diesel costs fell, keeping margins at historically high levels — while stopping short of finding profiteering. Its June monitoring work had already put average retail fuel margins at 11.3p a litre in April, against a 2025 average of 10.7p. We covered that in full in our piece on the CMA's findings on retailers being slow to pass on savings.
The regulator's stated expectation is that wholesale reductions should be passed through rapidly and fully. If crude holds at these levels into September, the next few weeks become a straightforward test of whether that happens — and, more usefully for you, of which retailers near you move first. That is not a national question. It is a local one, and the answer is different on every high street.
What to do over the next fortnight:
- Don't panic-fill. If your tank is half full and prices are drifting down, there is no advantage in brimming it today.
- Do check before every fill. Prices at stations a couple of miles apart routinely differ by 10p a litre or more — far more than any national average movement this week.
- Watch the movers, not the average. When falls do come, some forecourts cut within days and others take weeks. The gap between them is where the money is.
- Diesel drivers, watch the premium. At 21.19p it is unusually wide. If wholesale diesel eases, that is the number with the most room to move.
- Save your regulars. Adding the stations you actually use to Favourites makes a price drop obvious the moment it happens.
Where to check
Everything on this site runs on the Government's Fuel Finder feed, refreshed every 15 minutes across over 8,000 UK stations. The live price comparison shows what is cheapest near you right now, the fuel map puts it in geographic context, and the price charts and UK Fuel Price Index track the weekly national averages quoted above so you can see whether a fall is genuinely arriving. If you are planning a longer trip, the journey planner works out the cheapest places to stop along your route.
Sources and dates: UK pump prices are the Department for Energy Security and Net Zero weekly road fuel price statistics for the week commencing 24 August 2026, published 25 August. Crude prices are Brent benchmark levels as at 27 August 2026. Market and negotiation detail is drawn from contemporaneous market reporting, including Reuters, and from the US Energy Information Administration's August 2026 Short-Term Energy Outlook. Oil markets move fast and the diplomatic position described here may have changed since publication.