Crude Oil Types
Crude oil benchmarks, also known as oil markers, were first introduced in the mid 1980s. There are three primary benchmarks, WTI, Brent Blend, and Dubai. Other well known blends include the Opec basket used by OPEC, Tapis Crude which is traded in Singapore, Bonny Light used in Nigeria and Mexico's Isthmus.
Crude oils vary greatly in quality. The most important Crude Specifications are viscosity, measured in API units and Sulphur Level. API levels can vary between 10 and 50 with higher numbers indicating a lighter crude. Crudes with high levels of Sulphur are said to be Sour Crudes, whilst those with low levels are said to be Sweet.