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

What kind of transmission fluid to use

The type of transmission fluid you use will depend on the type of transmission you have in your vehicle. Automatic vehicles, of course, use automatic transmission fluid. For vehicles with a manual transmission, different oils are used, including ordinary motor oil, gear oil, or sometimes even – wait for it – automatic transmission fluid! Your car owner’s manual will tell you what your transmission requires.

How long does transmission fluid last?

Transmission fluid does need to be changed from time to time, and the most accurate answer to the question is that the fluid will usually last between 30,000 and 60,000 miles. That said, if your vehicle sustains heavy use, you could have to change the transmission fluid in as few as 15,000 miles. Of course, more frequent changes won’t harm your vehicle.

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

Another factor that can affect the life of your transmission fluid is the presence of contaminants. They have to be drained out, and if they aren’t, fluid life is going to be the least of your worries – you’ll be more concerned with the life of your transmission. If you’re lubricating your transmission with metal shavings and other nasty contaminants, at some point it’s going to develop serious problems. Regular transmission fluid changes are simply a good investment.

This article originally appeared on YourMechanic.com as How Long Does Transmission Fluid Last? and was authored by Valerie Johnston.


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