http://www.fxstreet.com/education/related-markets/oil-basis-grades-of-crude-oil/http://www.fxstreet.com/education/http://mediaserver.fxstreet.com/images/fxstreet-provider-logo1-en.gif7http://www.fxstreet.com/education/related-markets/oil-basis-grades-of-crude-oil/2008-12-10.htmlMany readers asked why London Brent crude futures price is always lower than Nymex WTI crude oil price. There's nothing related to exchange rate but quality of oil. Crude oil is classified into various grades according to density (heavy vs light) and sulphur content (sour vs sweet). The lighter and sweeter the crude, the higher the price it can be sold, because refiners can produce higher yield of high quality refined products from it. Density is measured by API gravity, a measure developed toWed, 10 Dec 2008 16:48:30 GMThttp://www.fxstreet.com/education/related-markets/contact@oilngold.com (Oil N' Gold)http://www.fxstreet.com/education/related-markets/oil-basis-grades-of-crude-oil/2008-12-10.html