Orient Electric OF0905F-Watt 9-Fins Oil Filled Radiator (Black/Silver) An oil filled radiator is a common form of convection heater used in domestic heating. Electricity is channeled into a resistor inside the heater, which turns the energy into heat. That heat is absorbed by the diathermic oil that is enclosed in the heater. As the oil in the heater warms up, it begins to circulate through the fins and columns. As the oil moves, it transfers heat into the metal of the heater's fins, creating an even surface temperature. As the metal fins heat up, they begin to radiate heat into the room. This heat is circulated throughout the room by natural convection in the air.