A pneumatic system installed on a vehicle and method of using the system to preheat compressor oil and/or components of the system to promote operation in cold weather conditions. The pneumatic system includes a compressor that generates compressed air in which oil is entrained, a separation tank that separates the oil from the air prior to the oil being returned to the compressor, and a heating element located within the separation tank and contacting the oil within the separation tank. Engine coolant of an engine cooling system of the vehicle flows through the heating element and the heating element transferring heat from the engine coolant to the oil within the separation tank to increase the temperature of the oil.