I am a former Hi Performance Auto Tech/Speed Shop owner and have used Mr. Thermostats for many years. Seal hello flow and I can tell you these thermos definitely flow by 15%. more coolant through the radiator and engine block. It keeps your engine temperature between 160 and 175 degrees, which is great for both performance and better gas mileage. If your car has an electric fan, I suggest hooking up a bypass to a switch in your car so you can turn it on and keep it super cool on a hot day. Itβ¦