[quote=JW51] Any engine that routinely runs 20 degrees over the thermostat setting either doesn't have enough radiator, or the cooling system is terribly dirty.
This! The other thing to keep in mind is that "engine temp" is not a uniform thing. The coolant enters the engine at its lowest temp, then picks up energy (and raises temp) as it goes through the coolant passages and comes out at its max temp. Because of that, some caution needs to be used when talking about "normal" engine temps because that will be affected by your measurement location.
As a specific example, an LS has the coolant temp port on the front driver corner, in the head. The heads are symmetric so you can add an additional one at the rear, passenger corner. It is fairly common to use the driver (stock) one for the ECU and put in an aux-sender for an aftermarket gauge in the passenger one. These two locations will read temperatures 15F-ish apart because the passenger side port is only about halfway through the coolant flow. I have seen plenty of people spend an inordinate amount of time trying to "fix" the operating temperatures from measuring it at a different place.
