IIRC a lot of older cars had the oil pump in the rear which would actually allow them to be push started and towed lond distances without problems. Somewhere along the way (I bet it came about the same time as Fuel Injection) the manufacturers figured out that the average car spends as much time ideling at lights or in traffic than it does moving so they moved the pump to the front where it would be run by the engine. This means you can't tow most momdern autos for long distances (such as behind an RV as you travel the US) or push start one, but it won't hurt to idel. I have found that my truck in very hot summer weather with the AC on max can overheat the eninge because the engine driven fan cannot keep up at idel speed. I have to shift to N and rev the engine a bit to get enough airflow. I'm planning on seperating the transmission cooler from the radiator and also installing an electric fan on the AC condenser to help out there.