Not all crude is the same barrel. These specifications determine refinery yield and processing difficulty — and therefore the premium or discount to the benchmark.
API gravity
A measure of how light a crude is: °API = 141.5 ÷ specific gravity (60°F) − 131.5. Higher is lighter; above roughly 31.1° is light, below 22.3° is heavy. Lighter crude yields more gasoline and diesel and generally commands a premium.
Sulfur — sweet vs sour
Below roughly 0.5% sulfur a crude is “sweet”, above it “sour”. Removing sulfur requires desulfurisation capacity, so sour grades typically trade at a discount — a gap widened by marine fuel sulfur regulation.
Total Acid Number (TAN)
Milligrams of potassium hydroxide needed to neutralise one gram of crude. A high TAN means naphthenic acid corrosion risk, which limits the refineries that can run the grade — and discounts it accordingly.
Pour point / wax
The temperature at which crude stops flowing. Waxy grades have a high pour point and need heated lines and tanks in cold climates, which feeds directly into logistics cost and delivery terms.
This reference explains published industry norms and standards. It does not replace the terms of an individual contract, nor legal or tax advice — and it carries no prices; the price board does that.