Oil filled heaters are also over 99 percent energy efficient. Almost all the electricity the consume is converted directly into heat. Since the resistor consumes the majority of the electricity used by a space heater, the less often if has to be activated, the more energy efficient your space heater will be.Click to see full answer. Moreover, do oil filled heaters use a lot of electricity?Oil heaters do take longer to heat a room but will provide you a more comfortable heating experience. Also the size of the room is a factor in cost efficiency. Oil filled units are the most efficient heaters. and often touted as 100% efficient, electric space heaters use a lot of electricity.Also Know, how much does it cost to run an oil filled space heater? The energy source in an oil-filled radiator is electricity. The wisdom of using an electric heater depends on the per kilowatt cost in your region. If your heater has a 1000 watt rating and your cost of electricity is $0.15/Kwh your cost to operate for one hour would be $0.15. Considering this, are oil filled heaters cheap to run? Oil-filled radiators are cheap to run – and there is no need to replace the oil.Which type of heater is cheapest to run?If a portable electric heater is definitely what you need, halogen heaters and oil-fired radiators are the cheapest to run, while bar fires and fan heaters are more expensive. The higher an appliance’s power rating in watts, the more it will cost to run.