So interesting question i have that i have never run into before. Just changed my radiator out but flushed the system before i changed it. so i put the new radiator and bled the system of air. let the engine get to operating temp and the fan kicks on. no erratic idle or anything. Heres the situation though. It will warm up to normal operating temp when im going slow through town or at idle but as soon as i hit freeway speeds or even about 55mph or so consistently, the temp gauge drops to below the meter but above the "C" in my crx. there is of course no signs of overheating as far as i can tell but even in my last rex when i swapped in a huge overkill fluidyne radiator it still stayed at a constant operating temp even while on the freeway. has anyone ran into this before or know what it might be? my first thought is thermostat isssue but i might be way off. any help?