I've just read this thread.
89 300CE runs just about 85C all the time. Creeps up a bit in traffic, but not much.
My question is: Shouldn't there be an "ideal" operating temp? For best cumbustion and fuel effeciency? If so, what is it?
When I bought this car my tech's advice was simple - Keep up with the oil changes and never, never let it overheat. It croaks head gaskets.
But I think mine should run hotter. Do thermostats come with a temp rating of some kind?