Transmission fluid being poured into a car

Transmission Fluid 101

The transmission of your car is the mechanism that allows power to be sent to the wheels as well as allowing the car to shift from one gear to another. In an automatic transmission, the transmission does this on its own, while a manual transmission will need the driver to shift gears. Either way, the transmission is going to require fluid to run smoothly and efficiently.

Why does the transmission need fluid?

Whether you have an automatic or manual, transmission fluid is going to be a necessity. While there are different fluids made for each type of transmission, most cars are made to accept automatic transmission fluid, or ATF, even if they are manual.

This fluid does many things for the transmission:

  • The moving parts in your engine's transmission need to be lubricated in order to move properly.
  • With all the moving parts, there is going to be friction, which in turn leads to heat. The transmission fluid helps keep these parts cool.
  • Transmission fluid, as long as it is maintained properly, can help keep the transmission clean.
  • Instead of parts corroding and wearing away, transmission fluid will keep them in the best condition for as long as possible.

When should transmission fluid be changed?

Most car manuals will suggest that the transmission fluid be changed every 30,000 miles. However, it may need to be done sooner if you are often driving in stop-and-go traffic or if you drive a large vehicle that tows or pulls heavy loads.

What happens if it is not changed?

Neglecting to change your transmission fluid can cause many future problems for your transmission. Instead of lubricating, the fluid will lose its viscosity and start causing even more friction. This concept combined with the slow loss of fluid means a greater chance for overheating. Instead of keeping the engine clean, the transmission fluid will be filled with debris and dirt which will simply be spread around. While none of these things will cause immediate detrimental damage, they can cause great problems in the long run if not addressed.

Can I change my own transmission fluid?

While most people choose to take their cars in to get the transmission fluid changed, it is possible to perform this on your own. Just like changing the oil, you will simply need to drain the old fluid and dispose of it properly and then fill the engine with new fluid. Then to locate the drain plug or pan, refer to your car's manual.

If you have questions or concerns about your transmission or its fluid, it would be best to visit a mechanic to ensure everything is working properly and is in good condition.

Last Updated: April 27, 2016