As the name suggests, transmission fluid is the liquid that lubricates and cools down the transmission parts. It comes in different variants and should be of the type as mentioned in the user manual. It helps clean the metal surfaces, conditioning the gaskets, and increase the rotational speed and temperature range. 

You can find out if the transmission fluid is at low levels from:

• The warning lights
• Overheating of the transmission
• Difficulty while shifting gears
• Leakage of the transmission fluid
• The problem of the transmission slipping

It plays a crucial role in increasing the lifespan of a lot of parts in a car. It is why we advise checking the transmission fluid timely and getting it refilled as and when necessary. Usually, we suggest replacing it at about 45,000 to 80,000 kilometers.