Abstract: Distillation system for distilling shale oil. Shale is inserted into a rotating retort which displaces the shale throughut the retort extended length. The rotating retort is mounted to a multiplicity of enclosed housings through rotative bearings. The enclosed housings form discrete heating chambers to provide individual temperature zones through which the shale passes in the distilling process. The multiplicity of housings are each connected to a next consecutive housing through a conduit which permits utilization of combustion gases from a common source to heat each of the temperature zones. A thermal control mechanism is coupled to each of the enclosures to provide temperature control within a particular temperature zone. Thus, the shale in its passage through the retort is subjected or exposed to predetermined temperature ranges within each of the enclosures for a predetermined time in order to maximize the efficiency of the shale oil recovery process.