Abstract: When heating indirectly the crude oil transported in pipeline, heat conducting oil, the heat medium, working always at high temperature, is bound to age and deteriorate. The deteriorated heat conducting oil, having higher acid value and gum cotent, may result in corrosion to pipeline, gum and asphaltenic deposit on pipe wall which may lead to decreased heater transmissibility of heat, even coking and punctures. In this case, the abandoned heat conducting oil has to be replaced. While the aging mechanism for heat conducting oil is described, a tentative idea is put foreward that travelling device for heat conucting oil regeneration shall be installed. Experimental tests show that lower costs and better oil quality can be realized by regenerating heat conducting oil and flushing the heater with the heat conducting oil.