The Nelson SPIRO-FIN Turbulator is a device which is placed inside the tubes of a heat exchanger to increase heat transfer efficiency from a viscous fluid which is intended to be cooled. The turbulators are comprised of an aluminum extrusion which has been twisted in the longitudinal dimension. The extrusions are twisted in order to increase the mixing of the fluid as it flows through the turbulator and therefore transforms the flow conditions in the boundary layer from laminar to turbulent flow. Without the turbulator the flow would be laminar throughout. Turbulent flow is characterized by a marked increase in heat transfer over laminar flow.