VISCOSITY BREAKING A cracking process; a rapid decomposition, usually conducted at low cracking temperatures (830° to 870° F.), to reduce the viscosity or pour point of a heavy, straight-run fuel oil. Viscosity Breaking Meaning A cracking process; a rapid decomposition, usually conducted at low cracking temperatures (830° to 870° F.), to reduce the viscosity or pour point of a heavy, straight-run fuel oil. Viscosity breaking,Viscosity Breaking Meaning,Viscosity breaking oilfield definition V,Viscosity breaking,Viscosity breaking meaning 24