Under severe driving conditions such as a lot of mountain pass driving or towing, this fluid may need to be serviced as often as every 15,000 miles. Most manufacturers recommend servicing automatic transmission fluid every 30,000-60,000 miles to keep the transmission operating optimally and to avoid expensive transmission damage. Corrosive fluid will cause premature gasket and seal failure which will eventually cause transmission fluid leaks. The metal particulates that build up in the fluid will also cause the fluid to become corrosive or acidic. Running contaminated or burnt fluid in the transmission will shorten the life of the transmission, cause shifting issues and could cause catastrophic damage. Degraded transmission fluid will have less viscosity, often have a burnt smell, and be discolored from the high amount of heat it is exposed to. Transmission fluid also breaks down over time because of the high amount of heat produced in a transmission. The metal particles then float around in the lubricant causing damage. Transmission fluid becomes contaminated overtime as clutch plates, gears and other internal transmission parts wear out. Transmission fluid also contains detergents that clean and remove build up on moving metal parts inside the transmission. Transmission fluid acts as a lubricant for all of the moving parts inside your transmission and serves as a coolant and a viscous fluid that transmits power from the engine to the transmission. Many variables related to how the vehicle is driven and the environment can affect fluids, so it must be scientifically analyzed to accurately know the fluid condition. Time and mileage alone are not the best indicator of fluid depletion or the breakdown of additive packages and sludge build up.

Transmission fluid viscosity tests