i have one but i dont use it. i just keep the cap off while the car is cold and warming up. i let it the radiator fan come on 2x. that usually warms the engine up to normal operating temp. when the coolant is moving smoothly i put the cap back on. turn the blower on high and the temp knob all the way to hot. watch for the temp gauge needle to rise to where it would sit warmed up. my car is a 92. this may not work on your car. on some newer cars not sure about hondas if the radiator cap is off the coolant wont circulate.as u drive the air will eventually work its way out.