EN590 vs ULSD vs Gasoil: A Buyer’s Guide to Diesel Specifications

Why specification matters

Buyers often request "diesel" without knowing which spec they need. The product they receive — and the price they pay — depends entirely on which specification is contracted.

EN590

European standard. Sulfur ≤10 ppm, cetane ≥51, density 820–845 kg/m³, FAME up to 7%, cold-flow grading by climatic class. Used in all EU countries for road diesel.

ULSD

US Ultra-Low Sulfur Diesel. Sulfur ≤15 ppm. ASTM D975 specification. Used for US road diesel, marine, and rail. Convertible to EN590 with additional desulfurization.

Gasoil

Generic term for middle-distillate fuel. Could mean heating oil (red-dyed gasoil), marine gasoil (DMA, DMB grades), or off-road diesel. Sulfur range varies wildly. Always demand a specific ISO or EN spec — never accept "gasoil" as a contractual product.

AGO

Automotive Gas Oil — typically refers to higher-sulfur diesel grades (500–5000 ppm) used in markets without low-sulfur regulation. Common in West African specifications. Cheaper than EN590 but not legal for road use in EU/US/Canada.

D2

Russian/Soviet-era specification for diesel. Sulfur 2000 ppm originally, modernized variants exist. "D2" offers in 2026 are almost always either Russian-origin (sanctioned) or fraudulent. The spec is largely obsolete in legitimate trade.

Jet A1 vs diesel

Jet A1 is a kerosene-grade fuel with a higher flash point (38°C) and additive package for aviation. It is not a substitute for diesel and vice versa. Buyers occasionally try to swap — both directions create engine damage and regulatory exposure.

What to write in the SPA

Specify the standard, the year, and the parameters explicitly: "EN590:2017 + A1:2024, sulfur ≤10 ppm, cetane ≥51, FAME ≤7%, cold flow class F". Vague specs invite spec deductions and disputes.