You can decrease your engine operating temps with an aftermarket

thermostat. My personal opinion is to drop from 195 to a 180 but

others go with a 160. In some of the newer models a lower

thermostat may set a code for not getting to engine operating temp

within the set time. The engine temp is supposed to be 182 for optimum

combustion in the cylinder, from the engine building book i have read,

but going lower will help reduce KR so there are some trade off's.

Another is if the oil becomes too cold it reduces its protecting qualities

in the same way as if it were too hot, but not as extreme. It has been

noted that if you want to drop to a 160 and are throwing codes then

you can spoof out the IAT with a 4.7K - 7K resistor and it will stop

setting the DTC's. If your PCM is not aftermarket then while sitting

still the temperature will still go to 210 which is when the fans kick on,

but while moving the temp should hover right around your selected

thermostats temperature.

 

My drilled 180------------------------------------------------------------------>

 

Another modification to the thermostat is to drill holes in it. This makes sure that even if the thermostat is closed there is still some coolant flowing thru the heads. If the thermostat were closed and didnt have holes in it then the coolant would not be moving and the coolant in the heads by the combustion chamber would be much hotter than the coolant over by the thermostat. So it takes longer for the thermostat to decide to open and cool the heads, and if the heads are getting hot youre going to start getting KR. Here is a better explanation: http://zzperformance.com/zzp/info/info_thermostat_holes.htm

 

So another opinion im going to throw out there is to run a 180 drilled at the track and during summer, then switch back to stock 195 in the winter. Thats what i do anyway, though a drilled 160 may yield more at the track if you are getting some KR. I drilled a bit too big of holes in mine otherwise i would probably run it in the winter but it takes longer than i drive to work to start putting out much heat and the gauge doesnt move. Once warmed up it keeps the coolant at about 167. You should drill 2-4 1/16" holes in it if you are going to do it. I put 4 1/8" holes in mine and thats too much. I probably should have only drilled 2 at 1/8".