Why did the 3:2:1 crack spread narrow to 57.8 this month?
The 3:2:1 crack spread is 57.8, down 14.42 over the past 30 days. The number is the theoretical margin on turning three barrels of crude into two of gasoline and one of diesel, and a working refiner watches it the way a trucker watches diesel at the pump. A move that size over a month is worth understanding before you decide what it means for the barrel you are about to run.
A crack spread narrows for one of two plain reasons: crude got more expensive, or the products made from it got cheaper. So I started on the crude side. WTI is 82.51, up 4.1% over 30 days. Crude firmed, but only a little, and the month around it was wide, with a 30-day high of 108.66 and a low of 68.25. A 4.1% rise in the input does not, on its own, account for a 14.42 drop in the margin. Crude is part of the story, not the whole of it.
That points at the product side, and gasoline is where the weight is. In a 3:2:1, two of the three product barrels are gasoline, so gasoline moves the blended margin more than anything else. RBOB is 2.958, down 11.3% over the past 30 days, near the bottom of a range that ran from a high of 3.761 to a low of 2.756. Gasoline is the biggest single input to the spread and it fell hard while crude rose. That combination pulls the crack down on its own, and it is the clearest driver in the data.
Diesel is pulling the other way. U.S. diesel is 5.652, up 6.4% over 30 days, and that figure is also its 30-day high. So the distillate leg of the crack is not weak at all. It is at the top of its month. The trouble for the blended number is arithmetic: diesel is only one barrel in three of the 3:2:1, so its strength cushions the spread without offsetting a gasoline barrel that is down 11.3% and a crude barrel that is up 4.1%. A strong minority leg loses to a weak majority leg.
Why diesel is holding up is worth a look, because it changes where the money actually is. RBN Energy reported this month that distillate stocks are on track for their lowest end-of-month level since April 2005, and that this was the lowest August inventory reading since 1951. FreightWaves ran an interview under the plain title that diesel is a refining problem, not a crude one, with diesel still above $5 and the cause put on refinery outages, low distillate inventories, and the Russia-Ukraine war still hitting the market. On that last point, the wire this month carried drone strikes leaving smoke over the refinery at Ufa, which is refining capacity taken offline. Tight distillate and lost refining runs keep diesel bid even as gasoline slides.
So the crack narrowed mostly on gasoline, and the margin that remains is landing on the diesel barrel. A refiner whose yield leans toward distillate is having a good month on the product it makes most of, earned on a real shortage of that product. A refiner or a blender weighted toward gasoline is watching the better part of its margin compress, because gasoline is down near the floor of its 30-day range while the crude it buys ticked up. The single blended figure of 57.8 hides that split. It averages a strong diesel leg and a weak gasoline leg into one number that looks worse than the diesel side of the business feels and better than the gasoline side does.
Retail data fits the same picture. Diesel's retail-wholesale spread is 1.384, up 0.183 over 30 days. The marketer and retailer margin on diesel widened while the wholesale price was rising, so the strength on the distillate barrel is showing up downstream at the rack and the pump, not just at the refinery gate.
On the crude side, the news reads loose rather than tight, which is consistent with WTI only rising 4.1%. Qatar and Kuwait have restored about 70% of pre-war oil exports through the Strait of Hormuz, per traders cited by Bloomberg, and prices fell for a fourth straight day on reports that Qatar's prime minister would visit Tehran to discuss reopening the strait, with Brent around $87.46 and WTI at $81.83 at the time of that report. Crude supply working its way back through Hormuz caps the input cost. It does not explain the narrowing, since crude still finished the month up, but it tells you the squeeze is not coming from the barrel going in.
What I am sure of: the narrowing to 57.8 is mostly the gasoline leg, with RBOB down 11.3% while crude rose 4.1%, and diesel is the strong leg holding at its 30-day high on genuinely tight distillate. Where the margin is landing is the diesel barrel and the diesel refiner, with the gasoline side carrying the compression. What I am less sure of is how long the split holds. Distillate that low could keep diesel firm into the fall, but gasoline could steady if crude keeps easing back through Hormuz, and the blended 57.8 would read differently the moment either leg moves. For now the honest answer is that the crack fell on gasoline and the money is in diesel.
And that was just the data. See you tomorrow.