A Refinery Buys Crude and Sells the Spread
An oil refinery makes money on the gap between what it pays for crude and what it sells the fuels for. That gap, the crack spread, decides whether the refinery runs at all.
What a Refinery Actually Sells
A refinery buys crude oil and processes it into refined products: gasoline, diesel, jet fuel, heating oil and others. It does not profit from the oil price rising or falling. It profits from the difference between the cost of the crude it buys and the value of the products it sells.
That difference is the crack spread, named because refining cracks crude into lighter products. It is the single number that determines whether a refinery is a good business at any given moment, and it moves independently of the oil price itself.
A refinery is not a bet on oil. It is a bet on the gap between crude and the fuels made from it, and that gap can widen while oil falls or narrow while oil rises.
Why the Spread, Not the Price
Because the refinery buys crude and sells products, a rise in the oil price raises its input cost and, usually, its output prices together. What matters is whether product prices rise by more or less than crude, which is exactly what the crack spread measures.
A refinery can be highly profitable when oil is expensive, if fuel prices are even higher relative to crude, and unprofitable when oil is cheap, if fuel prices have fallen further. The oil price alone tells you almost nothing about refining profitability.
| Situation | Crude | Products | Refinery |
|---|---|---|---|
| Strong fuel demand | Rising | Rising faster | Wide spread, profitable |
| Weak fuel demand | Falling | Falling faster | Narrow spread, loses money |
The Run or Shut Decision
When the crack spread narrows enough, a refinery loses money on every barrel it processes, because the products are worth less than the crude plus the cost of running the plant. At that point the operator faces a decision: keep running at a loss, or reduce rates and shut units.
Refineries prefer to keep running because starting and stopping is expensive and slow, and because a refinery has fixed costs that continue whether it runs or not. But a sufficiently negative spread forces reduced runs, which removes product supply from the market and eventually helps the spread recover. This is the self correcting mechanism of the refining cycle: poor margins reduce output, which tightens supply, which restores margins.
Not All Barrels Are Equal
Crude oil is not a single substance. It varies by density, from light to heavy, and by sulphur content, from sweet to sour. Light sweet crude is easier and cheaper to refine into valuable products. Heavy sour crude is cheaper to buy but requires more complex and expensive processing.
A refinery configured with sophisticated equipment can process cheap heavy sour crude into valuable light products, capturing the difference between the discount on the crude and the value of the products. This complexity is a durable advantage, since a complex refinery can buy the cheapest crude and still make high value fuels, while a simple refinery is limited to lighter, more expensive feedstock.
The Product Slate
A refinery does not choose freely what to make. The mix of products, the product slate, is constrained by the crude and the equipment, though it can be adjusted somewhat toward whatever is most valuable.
The relative prices of different products matter. When diesel is valuable relative to gasoline, refineries shift toward maximising diesel within their constraints. Seasonal patterns, more gasoline demand in summer driving season, more heating oil in winter, drive predictable shifts, and refineries plan maintenance around them, taking units down in the low demand shoulder seasons.
Why Location Matters
Refining margins vary by region because both crude costs and product prices are local. A refinery with access to cheap local crude and strong nearby fuel demand enjoys structurally better margins than one that must import crude and export products.
This is why refining is not a uniform global business but a set of regional markets, and why the same crack spread can mean prosperity in one region and closure in another. Refineries in disadvantaged locations close permanently when their structural margin disappears, which removes capacity and, over time, supports margins for those that remain.
The Bottom Line
A refinery earns the crack spread, the gap between crude cost and product value, which moves independently of the oil price and determines profitability directly. When the spread narrows enough, the refinery loses money on every barrel and reduces runs, which tightens supply and restores margins in a self correcting cycle. Complexity, the ability to process cheap heavy crude into valuable products, is the durable advantage, and location determines which refineries prosper and which eventually close.