Purpose

• Block heaters are electrical elements installed in car or truck engines to keep them warm when winter temperatures drop below freezing. Using a block heater reduces the likelihood of being stuck when your cold engine won't turn over and start on a cold winter morning.
  
  

Method

• A block heater is plugged into an electrical outlet and uses the supplied electricity to keep engine coolant warm. This helps keep other engine fluids, such as oil, warm and makes it easier for the engine to start when temperatures are well below freezing. As an added bonus, engines warmed with block heaters can have their fuel economy improved by as much as 10 percent.
  
  

Cutting Costs

• Don't keep your block heater plugged in all night, or when the temperature is warmer than 14 degrees Fahrenheit. Block heaters don't need to be plugged in for any more than two to four hours, so you can cut electricity usage by connecting the block heater to a timer. According to the website Climate Change Central, block heaters can use as much as eight times more energy than a refrigerator.