“During the winter, running the heater can slightly improve efficiency of a gasoline or diesel engine by increasing the heat rate.”
Well I did just start doing this a couple months ago and when winter hits I do plan on using the heat again. Thank you for putting to rest any doubts that I or anyone reading this thread may have had about the efficiency issue, I had no idea.
I used to drive some clunkers. Having a problem with the engine cooling like closed off tubes in the radiator could be compensated by running the heater full blast, as long as you got some coolant circulation. Not so bad in a cold winter, a lot less fun in July.