Fuel buyers live with a price that moves daily and explanations that rarely go past "oil went up." The real machinery is knowable, and knowing it changes how you buy: what benchmark your price should reference, which parts of the stack are negotiable, and when locking a price is protection versus speculation. This is the plain-language version of how a gallon gets its number.
The stack: what a gallon is made of
Every delivered gallon is four layers. Crude oil is roughly half the price in normal markets: the raw material, set globally. Refining margin, the crack spread, is what the market pays to turn crude into gasoline or diesel, and it breathes with refinery outages, seasons, and inventories. Distribution and marketing covers pipelines, terminals, trucks, and the margins of everyone who touches the gallon after the refinery, including your supplier. Taxes finish the stack: federal excise at 18.4 cents on gasoline and 24.4 on diesel, Texas at 20 cents on both, other states higher, all fixed per gallon regardless of market level, and all skippable only where the law says so, dyed off-road fuel being the big case. When your price moves, one of the first three layers moved; knowing which one is the difference between an explanation and a shrug.
The reference points: futures, spot, rack
The visible skeleton of fuel pricing is the futures market: NYMEX RBOB for gasoline and ULSD for diesel, both priced for delivery in New York Harbor, are the numbers on every trading screen and the anchor for everything downstream. Physical trade happens against them: spot markets in the big supply regions, the Gulf Coast above all, price actual pipeline barrels at differentials to the screen, and the terminals convert it all into the number that matters to buyers, the rack price, posted at each terminal where trucks load, by product and seller, updated daily or faster. Published services compile these postings into indexes, city averages and low racks, and that's what honest supply contracts reference: a number both sides can look up, not a number one side declares. Regional basis does the rest: distance from supply, pipeline space, and local disruptions make El Paso and Houston different markets on the same afternoon.
Why diesel and gasoline dance differently
The two products share crude and little else. Gasoline demand follows wheels: summer driving peaks it, and the seasonal spec change adds its own step, since summer blends cost more to make. Diesel is a distillate, cousin to heating oil and jet, and its demand runs on freight tonnage, harvests, and winter heating across the whole hemisphere, which is why a cold snap in Europe can raise the price of a Texas truck stop's diesel. Add diesel's higher excise tax and the premium swings both ways by season: diesel over gasoline through winter and strong freight markets, gasoline clawing back in driving season. A buyer who burns both should expect their two prices to diverge and stop treating the gap as a supplier mystery.
Buying it right: structures and the honest quote
Wholesale fuel trades in a few clean structures. Index-plus, rack average or screen plus a stated margin, is the workhorse: transparent, comparable between suppliers, moving with the market both directions. Fixed-price locks a number for a volume and period, the right tool when a bid or budget needs certainty, priced off the futures curve and best understood as insurance, not a market call; caps and collars split the difference for a fee. Spot buying takes each day as it comes and suits opportunistic storage more than operations. The evaluation discipline is the same for all of them: compare quotes on the same index, same date, same terms; get the margin stated, not blended; and remember from the economics guide that the cheapest cents-per-gallon quote is not the cheapest fuel program once minutes, shrinkage, and paperwork are priced. A supplier confident in its margin will happily show you the index; that willingness is itself the credential.
Common questions
Why do prices rise fast and fall slow?
Partly real: replacement cost hits sellers immediately on the way up, while falling markets drain through inventory bought dearer. Partly commercial behavior in less transparent price structures, which is one more argument for index-referenced contracts where the pass-through works identically in both directions.
Does a big buyer really get a better price?
Volume earns its discount in logistics, not magic: full transport loads, efficient routes, and predictable schedules cost the supplier less and the savings are shareable. That's why a yard tank sized for full drops usually beats piecemeal buying on price alone.
What moves the market that nobody watches?
Refinery maintenance calendars, pipeline allocations, spec transition dates, and inventory reports move racks more week to week than the headlines do. A supplier who reads those and tells you what's coming is doing half your purchasing job for you.
The series, and where Vexon fits
Previous: standby and generator fuel. That closes the fuel series; it starts at diesel quality, and the whole library lives on the knowledge hub. Vexon prices on transparent indexes, NYMEX, spot, and rack, with the margin stated: get in touch for a quote you can check.