Thermostats play a vital role in engine management. Thermostats can fail in 2 possible manners; open or close position. If stuck open, the engine's heater will operate at reduced efficiency for an extended period of time or if stuck shut, will cause your car’s engine to overheat leading to costly repairs or ultimately “complete engine failure”. The Aeroflow Performance range of GM LS thermostats are available in two temperatures that are lower than the factory units. Reducing the temperature which an engine runs will make more power through better thermal and volumetric efficiency. This is a direct drop in with no modifications needed and includes the rubber seal.