An injection nozzle that can be used in an injection blow molding system without use of an external heat source comprises a two-piece structure broadly including a structural outer body for coupling the nozzle to a resin manifold and a thermally conductive insert. At least a portion of an axial length of the insert has an outer diameter that is less than an inner diameter of a coinciding coaxial portion of the outer body, such that the differences in the inner and outer diameters present an insulating air gap along at least a portion of the nozzle length. A sufficient operating temperature for hot melt resin can then be obtained without use of the external heat source.