 The high specific heat capacity allows the oil to effectively transfer thermal energy from the heating element, while the oil's high boiling point allows it to remain in the liquid phase for the purpose of heating, so that the heater does not have to be a high pressure vessel.The heating element heats the oil, which transfers heat to the metal wall through convection, through the walls via conduction, then to the surroundings via air convection and thermal radiation.The columns of oil heaters are typically constructed as thin fins, such that the surface area of the metal columns is large relative to the amount of oil and element which provides the warmth.