Transmission fluid is a slippery liquid that acts as a lubricant for all of the moving parts inside your transmission. In an automatic transmission, this fluid also serves as a coolant and a viscous fluid that transmits power from the engine to the transmission.
It’s important to regularly check the transmission fluid level between service intervals. Letting your car run low on transmission fluid can cause the transmission to shift improperly or not at all. It also can harm the internal parts of your transmission, which will not be properly lubricated. Unfortunately, you may not hear any noises or have other clues that your transmission is low on fluid, until it’s too late. So it’s important to get it checked.
You need to check/change transmission fluid regardless of whether you have a manual or an automatic transmission.
Manual: In a manual transmission, the problem is not so much the fluid degeneration, but rather fluid contamination. This contamination occurs over time as the synchronizers, bearings and gears in the transmission wear out. The resulting metal particles then float around in the lubricant. And we all know that oil with microscopic particles of metal in it does not lubricate as well as clean oil. So if these contaminants are not drained out, They will shorten the life of your transmission.
Automatic: Because more heat is generated in an automatic transmission, automatic transmission fluid actually degrades and breaks down with use.
In addition, like in a manual transmission, automatic transmission fluid will also become contaminated with worn bits of the transmission. If these contaminants are not drained out, they will shorten the life of your transmission.
If you don’t change the transmission fluid on schedule, you’ll be lubricating your transmission with metal shavings and other contaminants. This will shorten the transmission’s life. The result could be a hefty payment to your mechanic. In other words, changing your transmission fluid at the correct.