Fitment and Product Information. Thermostatically Controlled LS Engine Oil Cooler Bypass Adapter Kit. Brandname: Derale Part Number: 35621 Description. This Billet Aluminum LS Engine Adapter features a built in 180°F Thermostat to help reduce engine wear and horse power loss. The oil thermostat allows the oil to bypass the cooler until it reaches 180°F at which point the internal thermostatic valve will close and force 100% of the oil through the cooler while maintaining a constant pressure system. This process allows the engine to achieve the ideal operating temperature quicker before passing the oil through the cooler. Bypasses cooler until fluid temperature reaches 180°F. Provides quicker warm-up temperatures. Perfect for cold weather climates. Flows up to 20 gallons per minute. Rated up to 200 psi. 10AN ORB inlet/outlet ports for maximum flow. WARNING : This product can expose you to chemicals including Styrene, which is known to the State of California to cause cancer.