[s-cars] S-CAR-List Digest, Vol 74, Issue 104

[J. Khang]

> Tony;
>
>Stick with the 87C thermostat.
>
>With the 80C thermostat, the engine will run too cool in the winter. The
>higher temperature increases operating efficiency and reduces fuel
>consumption.
>
>Contrary to popular belief, the 80C thermostat does not make the engine run
>cooler in the summer. If the rad isn't large enough to hold the summer temp
>to 87C with the thermostat fully open, it won't hold it at 80C either. On a
>hot summer day the engine temperature is determined by the heat input (how
>close to the floor is the gas pedal?) and the amount of heat the rad and oil
>cooler can shed at the ambient temperature.
>
>HTH
>
>Fred Munro
>'97 S6
 
The 80C thermostat does make the engine run slightly cooler. Air temperature during the day is rarely below 35C where I am and the CC display showed coolant temperature as high as 96C (traffic jam) but 89-91C was the norm. After I swapped in an 80C thermostat, I normally see 87C max.
 
Jonathan