All internal combustion engines have a "sweet zone" of operational temperature where the components are designed to perform at their best. Critical in both gas and diesel engines, this is the temperature range at which all of the operating systems of the vehicle are designed and engineered to provide the most efficiency and extended service life. Not exceeding these temperatures, especially for long periods, is crucial to the life of these components.
Transmission fluid temperatures are critical; unlike the radiator fluids which cool quickly, automatic transmission fluid can heat up rapidly and take a long time to cool down. The fluid serves three purposes in the transmission:it acts as a hydraulic fluid, it cools, and it lubricates the internal moving parts. Insufficient transmission cooling can cause premature wear or complete transmission failure. By periodically eyeing your transmission fluid temperature gauge, and knowing what your "high" should be, you will be able to recognize a problem developing before it becomes critical.
Hewitt fluid temperature gauges come with a variety of dial face colors, pointer colors and bezel styles.