I will add to that and say that hotter block/coolant temps lead to higher efficiency because you have less heat loss due to less temperature differential between the combustion chamber and the surrounding metal.
Ok but where people are drawing questions is once the stat opens the coolant is free to climb to whatever temp the ambient air and load dictate. I mean if a 180deg stat kept water or oil temps 20 deg cooler during a prolonged drive id be surprised. Ive never seen a difference. I changed water pumps and went to a cooler tstat last summer and my oil.still gets to.about 210 degrees once the truck is doing its thing.
Do yu have any ideas what effect 180 vs 200 deg water temp has on the temperature of a combustion.chamber or cylinder temps?