Oil inventory is the buffer between supply and demand. When a chokepoint like the Strait of Hormuz constrains crude flows, the shortfall is met first by drawing down stock — commercial tanks, the Cushing hub, the Strategic Petroleum Reserve — before it ever reaches the pump. Watching that stock fall is watching the buffer being spent. The US numbers above are weekly and precise (from the EIA); the OECD and European figures are monthly and lagged (from the IEA), so they tell you the direction and the cover, not a daily level.

What the latest EIA week shows

Week ending 18 September (EIA, released 23 September): US commercial crude built 3.0 Mbbl to 426.4 Mbbl, against a draw of roughly 0.6 Mbbl the market expected — the first build in four weeks, after three consecutive draws that had taken stocks from 424.4 to 423.4 Mbbl, and enough to put crude about 2% above its five-year average. The barrel is still splitting, and that is the part that matters. Gasoline fell 1.7 Mbbl to 206.0 Mbbl, and distillate fell 0.4 Mbbl to 107.5 Mbbl, 12% below its five-year average — the tightest part of the barrel for the fifth straight month. Total products supplied, a proxy for US demand, averaged 20.6 Mbbl/day over four weeks, up 0.5% year on year, with gasoline demand at 8.8 Mbbl/day. Crude building while distillate drains is why US retail diesel set another record at $6.5276 a gallon on 22 September while Brent was spending five sessions falling, and why the EIA projects distillate stays below its five-year low through much of 2027. It is also why Washington floated a 90-day diesel export ban this week, which the White House then denied. The Strategic Petroleum Reserve stands at 284.96 Mbbl for the week ending 11 September, its lowest since 1982 and about 40% of its 714 Mbbl authorized capacity, having fallen roughly 128 Mbbl since early April; weekly draws have slowed to about 0.4 Mbbl. A figure of about 284.6 Mbbl for w/e 18 September is circulating in coverage that otherwise reports the API estimate and predates the EIA release, so GEF carries the confirmed 11 September figure until a clean print is available. Source discipline: the API estimate for the week to 18 September (crude +1.8 Mbbl, distillate −2.2 Mbbl / 13% below) differs materially from the EIA print. GEF publishes the EIA figures.

Europe's oil position and the 90-day rule

Europe is the more exposed region, and it is governed by a hard floor: under the EU's emergency oil stockholding rules, member states must hold the equivalent of around 90 days of net imports in strategic reserve. That obligation is the backstop — but the working buffer above it is thin. On some measures, jet and middle-distillate cover has slipped below the IEA's roughly 23-day comfort threshold, which is precisely the stress that surfaces on the shortages map as European jet-fuel and diesel strain. Europe gets a fuller per-country treatment on the gas side; on oil, the days-of-cover figure is the metric to watch.

What we track precisely — and what we don't

Honesty about sourcing is part of the point. Here is the line between the measured and the estimated:

• Precise & weekly: US commercial crude, Cushing, the SPR, gasoline and distillate — all from the EIA Weekly Petroleum Status Report.
• Precise but monthly/lagged: OECD and EU commercial stocks and days of cover, from the IEA Oil Market Report.
• Qualitative only: crude on water (floating storage), ARA refined-product stocks in north-west Europe, and Chinese and Saudi domestic reserves. These are either paywalled or genuinely opaque, so we describe their direction in words rather than publish a precise number we cannot stand behind.

Inventory cover is the countdown that connects the chokepoint to the checkout. A blocked strait does not cause a shortage on day one; it causes a drawdown, and the shortage arrives when the drawdown runs out of room. Today the buffer is uneven rather than uniformly thin. The SPR is at its lowest since 1982; commercial crude, by contrast, is about 2% above its five-year average after a 3.0 Mbbl build; and distillate is 12% below its five-year average with retail diesel at a record. The crude barrel is available and the refined product is not. The global product pool is under a second, separate pressure: Ukrainian drone strikes have repeatedly hit Russian refining — Reuters reported on 15 September that Kinef was shut and Volgograd and NORSI were running at about 25% of capacity, three of the six plants that make roughly half of Russia’s diesel. That tightens the same pool the US and Europe draw on, on top of the Hormuz-driven crude story above, and it is why Washington’s floated-then-denied diesel export ban mattered to Europe. That is why this page sits alongside the chokepoint transit data and the shortages map: one shows the disruption, one shows the buffer, and one shows where the buffer has already run out.