OK, I am not sure if I understand something here.
My L03's fan turns on at what the tewmp gauge shows to be 240-245*.
I've heard that the temp gauge is not very accurate - but mine appears to be somewhat accurate, as when I am sitting with ac on (so fan in on), it will run about 190-200, same with if I am cruising highway. So, that means my fan switch is set for 240*?!?!? Why would GM do this - it CANT be good fer an engine to run THAT hot...can it?

 

get a low temp thermistat and a new lower temp fan switch and see where that gets you...

 

On your setup the stock turn on temp is 238. It is not a problem at all. All modern cars are designed to run hot because of emissions and fuel economy. I would not change the thermostat as the engine will tend to run rich and fuel economy will suffer. NAPA stocks a fan switch that will turn on your fan at about 215. Problem is that the fan will cycle much more often. If you have any worries I would change to a synthetic oil. That is a bigger concern the hotter engines are being run.

 

i wouldnt want my car to run that hot and it doesnt now. at least get a 180* thermostat. then from there add a low temp switch

 

Well, now the ECM/PROM is all set up to run at those temps. Now, my engine seems to make the most power at the mark between 100 and 220, but, since I dont race, and I like my money, I think I will keep the thermo stock, because it would only make sense to get better gas milage at the operating temps its set up for. I just was curious. But if its actaully supposed to run that hot, then I am not truely worried.

 

Buck, the thing many of the guys seem to miss is that coolant temp is not really reflective of combustion chamber temp. A 10 degree difference in coolant temp means little as far as engine longevity is concerned. The critical thing is as you pointed out, that the ECM is looking for a target temp for it to execute it's closed loop programming. I go back to the late 60's and early 70's and even then we always had an oil temp guage to determine our safety margin. When one takes into account that only one third of the heat energy is actually transmitted into moving the piston it is no wonder the engineers are trying to design hotter running engines. Anywhere from 195 to 240 is a fine operating range as long as the temp is maintained fairly constant. Colder stats generate a large temp swing which is really more detrimental to long term engine life. I have found that the oil is really important. For example if I run 5-30 dino oil in my other 3 cars they would always need to be topped off. GM in a recent TSB says one quart every 4K is acceptable. Put in a synthetic oil and I never have to add any even with an extended change interval. If you have any worries at all change over to Amsoil or Mobil1 and you will be better off than trying to alter the temp 10 degrees or so. Just my 2C

 

Danno, you sound like you've "been there, done that". You pretty much reitterated what I've said. Thank you for affirming my thoughts. I think I'll stay stock...