block heater vs radiator

block heater

noun
  • An electric heater that heats the engine of a car to ease starting in cold weather. 

radiator

noun
  • A device that lowers engine coolant temperature by conducting heat to the air, through metal fins. 

  • A type of antenna. 

  • A finned metal fixture that carries hot water or steam in order to heat a room. 

  • Anything which radiates or emits rays. 

How often have the words block heater and radiator occurred in a corpus of books? (source: Google Ngram Viewer )