Subaru Thermostat - STI 04+ Gates Finishes used by other manufacturers

Finishes used by other manufacturers provide only minimal protection from the elements and are generally only effective for the shipping and storage portion of a rotor’s life

making the device waterproof and safe to wash

Underbody components such as front air dams

and rapid heat dissipation

Replace when dirty to maintain peak performance power

Subaru Thermostat - STI 04+ Gates Finishes used by other manufacturersCooling System Repair or ReplaceIf your thermostat has failed, it can stick open or stick closed. A thermostat that's stuck closed will result in an overheat that happens after the engine has been running for a few minutes. If it's stuck open, the engine will never reach proper operating temperature. Both can do long term damage to the engine in your 2018 Subaru STI, so contact a Subaru technician.