The Audi S4A4A6 is a well - balanced vehicle that demands a reliable and efficient cooling system to perform at its best.Keep your Audi on the road and out of the shop by upgrading to the Mishimoto racing thermostat.This thermostat promotes greater cooling efficiency by significantly decreasing high engine temperatures.Once the engine is fully warmed up, the Mishimoto low - temperature racing thermostat will open at a lower temperature (160 F) compared to standard thermostats (189 F).This allows coolant to flow through the engine sooner, thus reducing and maintaining cooler engine temperatures.As with all our products, this thermostat includes the Mishimoto lifetime warranty.