Refined Products at the Desk: Gasoline, Diesel, and Jet Fuel Specs, Blending, and Where Adulteration Enters

A cargo of crude oil is, in a sense, a raw material: whatever it is, it is. Refined products are different in a way that changes everything about how they trade and how they get defrauded. A cargo of gasoline or jet fuel is not really three hundred thousand barrels of liquid. It is three hundred thousand barrels measured against a written specification, and the moment the liquid stops meeting the sheet, it stops being the product at all. That single fact, that the product is the specification, is where blending economics, adulteration, and certificate fraud all live. This piece walks through the three most-traded product families, how refiners blend to hit the sheet, where the bad actors enter, and the inspection structure that actually protects a desk.

A Refined Product Is a Specification, Not Just a Barrel

Every products trade runs on a quality document: ASTM D4814 for US gasoline, EN 228 for European gasoline, EN 590 for European automotive diesel, ASTM D975 for US diesel, and for jet fuel, ASTM D1655 or the UK DEF STAN 91-091 for Jet A-1. These standards define the measurable parameters the cargo must meet, and the sale contract incorporates the sheet by reference. Off-spec does not mean a discount. It very often means rejected cargo, demurrage, and a claim.

The Specification Sheet at a Glance

Parameter	Gasoline (EN 228 / ASTM D4814)	Diesel (EN 590 / ASTM D975)	Jet A-1 (DEF STAN 91-091 / ASTM D1655)
Key performance parameter	Octane (RON 95/98 typical grades; RVP by season)	Cetane number (EN 590: min 51)	Flash point (min 38°C) and freeze point (max -47°C)
Sulfur	Max 10 mg/kg (Euro spec)	Max 10 mg/kg (Euro spec)	Max 0.2% typical (0.3% cap)
Notable constraints	Benzene max 1 vol%; oxygenate limits; ethanol capped by grade (E5/E10 in Europe)	Density 820-845 kg/m³; flash point min 55°C; FAME (biodiesel) content capped at 7% by EN 590	Smoke point min 25 mm; thermal stability test; stringent contamination limits

The parameters are not arbitrary. Octane and cetane are the performance the engine is paying for. Flash point on jet fuel is an air-safety limit, not a preference. And each parameter costs a different amount to achieve, which is the whole reason adulteration exists.

Blending: How a Refinery Hits the Sheet

A refinery is a blending machine. Gasoline at the rack is a cocktail: reformate for octane, alkylate for clean burning, FCC naphtha as the workhorse base, butane for vapor pressure in cold months, ethanol because mandates and octane economics say so. Diesel is straight-run gasoil blended with cracked components and kerosene, with up to 7% FAME in Europe. Jet fuel is the most protected: a kerosene cut that must clear flash, freeze, smoke point, and thermal stability, which is why jet is the most expensive cut of the barrel in most seasons.

Blending is legitimate and universal, but it creates the structure fraud exploits: the finished product's certificate describes a blend that met the sheet at the refinery gate on the day of certification. Between that gate and your discharge port sit pipeline commingling (transmix, the gasoline-diesel interface material from multi-product pipelines), tank residues, barge heels of previous cargoes, water ingress, and every hand the cargo passes through. Each hand is an opportunity to either degrade the product accidentally or substitute something cheap deliberately.

Where Adulteration Enters

Adulteration is an arbitrage between specifications. The fraudster replaces an expensive component with a cheap one, betting the certificate will never be tested against reality:

Octane on paper. Cheap high-aromatic solvents blended into gasoline to fake octane performance, at the cost of engine deposits, emissions limits, and seal damage downstream. The certificate says RON 95. The engine says otherwise months later, in another country, with no claim trail.

The tax wedge. Diesel's most common fraud is economic rather than chemical: rebated agricultural or heating fuel laundered into road diesel. The fuel performs almost identically, which is exactly why enforcement runs on marker dyes and why laundering operations, well documented across the UK and Ireland in Europol and national enforcement reporting, strip markers with aggressive chemicals and dump the waste in the process. The cargo trades fine; the supply chain is criminal.

Solvent disposal by cargo. Waste solvents sold into product streams are the ugliest version. The documented 2007 UK contamination, where silicone-tainted fuel traced to storage-tank fouling forced a major retailer to pull gasoline nationally, showed how sensitive the system is: trace-level contamination, measured in parts per million, closed forecourts across a region.

Transmix and tank fraud. Interface material from pipelines sold as on-spec product, commingling into a dirty tank, or water and sediment left from a barge's previous cargo. None of these require a sophisticated counterparty. All of them defeat a buyer who relies on the load-port certificate.

What's Actually in Front of the Trader

By the time a products offer reaches a desk, the certificate of analysis is the product's biography, and the first question is who wrote it. A refinery CoA is a claim. An independent inspector's certificate, drawn from properly sampled, sealed, and retained samples at load and discharge, is evidence. The gap between the two is where product claims live: the seller points to the load-port CoA, the buyer points to the discharge-port assay, and the winner is whoever's samples were drawn under proper standard sampling practice, with intact seals and an unbroken chain of custody.

The Safeguard: Dual Sampling, Sealed Retention, and Delivered-Spec Terms, Broken Down

The products equivalent of the crude desk's dual-inspection safeguard has three moving parts:

1. Witnessed sampling at both ends. Independent inspection (SGS, Intertek, Bureau Veritas class) attending load and discharge, drawing samples to the governing standard, with the buyer's representative entitled to witness. Sample cylinders sealed and signed at the point of drawing. The sample is the entire claim; an unsealed sample is no sample at all.

2. Retained reference samples held by both parties. One sealed set for the seller, one for the buyer, one neutral. Quality disputes are then decided by testing the retained samples at an agreed laboratory, not by arguing. The arbitration clause names the lab and the test methods before anyone disagrees.

3. Delivered-spec contract terms. Where the desk has leverage, contract on spec as delivered at discharge port, not spec at origin. That single drafting choice moves the quality risk back up the chain to the party that controls the blending and the custody, which is where the risk actually originates.

None of this detects a clever adulterant by itself. What it does is make the certificate testable, the samples defensible, and the fraudster's cheapest option, an unverified piece of paper, unavailable.

References & Source Records

• EN 228 and EN 590 specifications (European Committee for Standardization); ASTM D4814, D975, and D1655 (astm.org); DEF STAN 91-091 (UK MOD standard for Jet A-1).

• Europol and UK/Irish enforcement reporting on fuel laundering and marker-dye fraud.

• Documented 2007 UK silicone contamination incident affecting retail gasoline supply.

• ASTM standard practice for manual sampling of petroleum products (ASTM D4057 and related sampling standards).