Here on the Canadian prairies we get -40C regularly in winter - Silicone spray is the best. Soak a rag with it and generously apply it to the rubber. When we wash our cars here in the winter we always have a can of silicone spray and lock deicer in the car. After washing the car - lock deicer in each lock and a good wipedown of the door seals with a dry cloth -then a generous application of silicone and not more problems!