Summer or desert or Death Valley (in California, not that pile of concrete in Clemson) temps would still be within a reasonable range ...... if rest of cooling system is up to snuff. If one assumes the engine produces a fairly steady heat output when operated at a fixed speed, the radiator has to dispose of that heat, and the thermostat helps regulate the process. If you are cruising the highway at 60 mph that is 5280 feet per minute of air flow X the square footage of radiator, quite a bit of CFM. The warmer ambient air won't cool quite as good. When you cause the brake rotors to be firmly squeezed and pause to examine the fabulous traffic engineering (stuck at another red light) the engine is still hot, but water flow has decreased (belt speed) and the viscous fan is all you got, and I think my stock one was like 800 feet per minute at idle. So the temp will rise. At around 212 F the brain is beginning to sweat, so it turns on the electric fan to help out.

I run a 180F stat in my D1, and in summer I stay in the 180-190 range even at 70 mph. Mall crawling it can get to 200. Temps in my area can hit low 100 - 108 on some days. It is really tough on the vehicle used by adventure mom making the milk run in heavy traffic. The cooling system is sized for high way speeds. Radiator is just not that big, unlike a big piece of construction gear designed for always slow or stationary operation.

If in the summer you hit 212 know that things are supposed to get better. If they don't you need to take some action if temperature spikes, or if you find you are always in the 220's for example. But don't trust the gauge on this. The engines are made to run from 180 to 205. They don't explode everytime you get to 225. But how long do you want to bake something? The instruments allow you to operate at elevated temperatures for long periods of time, while telling you everything is normal. Show me the numbers and let me make up my own mind.

Some of the desert rats have rigged up head light washers to spray mist on the radiator, so they can get some extra evaporative cooling like on a long hill, etc.

 

I heated up my motorad 180 stat in a pot one day just to see when it opened. It didn't fully open until almost 190.

 

Maybe it's broketeded?

 

A lot less broken than the first one I bought that wouldn't open with the water boiling. When I get my 04 back I think I'm gonna have to give the grey warm weather soft spring a try.

 

[QUOTE=weepit;368725] i know dexcool is evil mine has never looked bad and i never lose any coolant anywhere QUOTE]

Dex is not really the devil its is that its higher maintenance and has a tendency to be more corrosive. Most are better off using traditional green coolant so that they don't have the hassle of maintenance. Any coolant can and will become acidic over time, and dex & air are a bad combo. If your system is free of air and maintained properly then its fine.