The thermostat regulates the temperature of engine coolant. Depending on the model, it opens in 60 to 90 Celsius, and closes again when the temperature is 5 to 10 C lower. In other words, the thermostat mixes the cooler liquid in the radiator to cool down the engine, and also helps the engine to reach the optimal operating temperature quickly by only allowing flow through the radiator when it is needed.
Effect on engine temperature
An 80 C thermostat does exactly what you think, it tries to keep the engine coolant temperature at 80 C.
In hot conditions, a cooler thermostat might be needed, because it allows coolant to flow through the radiator sooner, and thus increases cooling efficiency.
As a contrast, in cold conditions a hotter unit is needed because the radiator is simply too effective when combined with a cooler unit.
The radiator only cools what flows through it.
Effects on interior heating
The heater takes it's heat from the cooling system. Having a cold thermostat and thus colder coolant reduces it's output, and having a hotter thermostat will provide more heat into the cabin too.
Choosing the correct one
If your car takes long to heat, and/or you are not satisfied with the heater power, you should get a hotter unit. If the car heats up in traffic, you should get a cooler one to increase radiator efficiency.
If the car doesnt warm up at all, the thermostat is most likely stuck open. This means coolant constantly circulates through the radiator not allowing the engine to heat up to normal temperature. In contrast, if it's stuck close, the car will overheat very quickly, usually in a matter of minutes.We offer these for most common cars, and all the thermostats we sell are of OEM quality.In addition to these, we have the Red Line water wetter additive as well as a big selection of radiators and water pumps which will rid you of all cooling issues for good!