A lubricating/detaching/fluidifying additive composition for organic polymers is described, comprising a saturated hydrocarbon having from 25 to 35 carbon atoms with at least three side substituents consisting of a methyl group, combined with at least one polysiloxane polymer having a molecular weight higher than 500,000. The use of this composition or single hydrocarbon component as lubricating/detaching/fluidifying additive for organic polymers, is also described, together with a polymeric composition containing additives, comprising an organic polymer and the additive composition.The use according to the present invention is particularly advantageous as it is universal (the same additive for all organic polymers, regardless of their formulation); it allows the use of high viscosity/high M.W. polymers (suitable for extrusion), also in injection moulding, and enables the additive to be applied externally to the polymer.