I want to change the thermostat on my car, but I don't know what temp. to get. I've seen 180, 175, and 160 degree for sale from various companies and I'm not sure which would be the best. Thanx for any help you guys can provide.

 

I put a 165 degree one in mine. You didn't mention which generation you have, though. In a C5 (and I assume the same in a C6) changing the thermostat alone does little good -- you have to also change the PCM to turn the radiator fans on at the lower temperature to really get the engine to run cooler: the engine control computer decides when to do that. Without the fans coming on earlier all you get from the lower thermostat is about a 5 degree drop - just pushing water through the radiator more.

((Note, too, as I understand it, there is still no reprogrammer/edit program available for the C6))).

 

I have a C5 (1998). Are there any negative side effects to using a lower temp. thermostat?

 

Not that i know of. i suppose it takes longer to heat up in winter so the heater works really well, but . . .