As a genuine Subaru part, the 21210AA181 thermostat is manufactured to deliver optimal performance and reliability, ensuring your vehicle runs as intended. OEM Subaru parts are known for their high-quality materials and construction, making the 21210AA181 thermostat more durable and less prone to failures compared to aftermarket alternatives.  A functioning thermostat ensures proper engine cooling, which helps prevent overheating, corrosion, and damage to engine components.