That viscous juice that's sloshing around and lubricating your motor's guts works best at a specific temperature range, and it's the job of the oil thermostat to keep an eye on just how hot your 10W-40 is. Without a fully functioning oil thermostat, your engine oil can easily overheat and cause some seriously costly damage. When you need a new oil thermostat but don't want to pay the crazy dealership's prices for parts, turn to AutoAnything. We have OEM-grade oil thermostats at guaranteed low prices, and they all come with free shipping.