How long does transmission fluid last?

Transmission fluid lubricates all moving parts of your car's transmission, and in automatic transmissions, it also acts as a coolant and a viscous fluid that transfers engine power to the transmission.

What transmission fluid to use

The type of transmission fluid you use depends on the type of transmission in your vehicle. Automatic vehicles, of course, use automatic transmission fluid. Different oils are used for manual transmission vehicles, including regular engine oil, gear oil, and sometimes even—wait—automatic transmission fluid! Your vehicle owner's manual will tell you what your transmission requires.

How long does transmission fluid last?

Transmission fluid needs to be changed from time to time, and the most accurate answer to this question is that fluid life is typically between 30,000 and 60,000 miles. However, if your vehicle is subject to heavy use, you may need to change your transmission fluid after only 15,000 miles. Of course, more frequent replacements won't hurt your car.

The type of transmission can also affect the life of your transmission fluid. Fluid in an automatic transmission, for example, will decompose faster than in a manual transmission because the automatic transmission generates more heat.

Another factor that can affect the life of your transmission fluid is the presence of contaminants. They should be drained, and if they aren't, fluid life will be the least of your worries - you'll be more concerned about the life of your transmission. If you lubricate the transmission with metal shavings and other nasty contaminants, at some point it may have serious problems. Regular transmission fluid changes are simply a good investment.