Mishimoto Mopar Pentastar / Hemi Thermal Bypass Valve UpgradeThe transmission in your Jeep Wrangler is the heart of its drivetrain. Whether you're hauling groceries or hitting the trail, it's vital to keep it performing at its best, and keeping the transmission fluid cool is crucial to that goal. In an attempt to balance drivability and the health of your transmission, Jeep fitted a thermostatic bypass valve to the lines that feed the transmission cooler. This valve ensures fluid doesn't flow through the cooler