A method of upgrading a heavy crude oil (10) by thermally cracking (12) the heavy crude oil in a cracking vessel to convert a portion to volatile components (14) while simultaneously venting the volatile components from the cracking vessel. Tetrathydrofurfuryl alcohol is optionally added to the heavy crude oil feedstock before or during cracking. The vented volatile components are separated (16) into condensable volatile components (18) and non-condensable volatile components (20). The condensable components are collected and comprise cracked-distilled oil. The cracking residue (48) is removed from the cracking vessel and a cracking residue extract is prepared and mixed with the cracked-distilled oil to produce synthetic crude oil.