West Texas Intermediate crude
West Texas Intermediate crude, aka WTI, is the "light, sweet" crude underlying oil futures contracts on the New York Merchantile Exchange.
According to the U.S. Energy Information Administration in 2011, West Texas Intermediate (WTI) crude oil is "of very high quality and is excellent for refining a larger portion of gasoline. Its API gravity is 39.6 degrees (making it a “light” crude oil), and it contains only about 0.24 percent of sulfur (making a “sweet” crude oil). ... WTI is generally priced at about a $5 to $6 per-barrel premium to the OPEC Basket price and about $1 to $2 per-barrel premium to Brent, although on a daily basis the pricing relationships between these can vary greatly."