wikipedia heavy oil English heavy oil heavy heavy oil wiki extra-heavy crude oil “heavier” Heavy crude oil heavy crude heavy crude oil heavy oils heavy oil heavy oil heavy crude heavy crude extra-heavy oil heavy crude oil heavy oil heavy oil English heavy oil English Heavy oil view article English heavy oil extra-heavy crude oil Heavy oil heavy oil heavy oil Heavy oil heavy oil Heavy oil heavy oil heavy oil heavy oil heavy crude oil heavy oil heavy crude English Heavy crude oil heavy oil heavy oil Heavy oil heavy oil heavy oil heavy oil Heavy oil extra-heavy crude oil heavy crude English heavy crude English heavy crude oil. Heavy oil heavy oil heavy oil extra-heavy oil Heavy oil extra-heavy crude oil heavy crude heavy or extra-heavy oil heavy extra-heavy crude oil Heavy oil extra heavy crude Heavy oil extra-heavy crude oil heavy oil heavy oil extra-heavy crude oil heavy oil extra-heavy crude oil heavy oil heavy oils extra-heavy crude oil extra-heavy crude oil Heavy oil extra-heavy oil extra-heavy crude oil heavy oil heavy oil Heavy oil http://en.wikipedia.org/wiki/Heavy_crude_oil heavy oil extra-heavy crude oil heavy Heavy oil heavy oil