Can Changing Your Car’s Transmission Fluid Damage it?

Maintaining your car is just as important if you want it to last a long time. However, there are many different maintenance items to address, one of which is changing its transmission fluid on a regular basis. Whether it’s equipped with an automatic transmission or a manual one, your car has transmission fluid that will need to be changed regularly. But can changing this fluid actually damage the car?

How often should the transmission fluid be changed?

Two men check the transmission fluid level on a car.
Two men check the transmission fluid level on a car. | (Photo by Tim Brakemeier/picture alliance via Getty Images)

It varies. Every vehicle will have a different interval in which its transmission fluid needs to be changed, so be sure to refer to your car’s owner’s manual to find out. If you’re ever poking around underneath the hood of your car, then another way to check if the transmission fluid needs changing is to pull the transmission’s dipstick. Much like checking the car’s engine oil, you only need to pull out the dipstick, give it a wipe, and then reinsert and look at it again to observe its condition and level.

According to M&J Sunshine, there are markings on the dipstick that will indicate if the fluid level is low or normal. Also, the newer the transmission fluid, the cleaner and pinker it will be. As such, if you find that the fluid in your car is dirty or black, then it’s definitely time to change it. Keep in mind that many new cars today don’t have a transmission fluid dipstick, so you’ll have to get it checked by the dealer or a qualified mechanic.

Transmission change versus a transmission flush

Mechanics change the transmission fluid in a car.
Mechanics change the transmission fluid in a car. | (Photo by Sandy Huffaker/Bloomberg via Getty Images)

If you decide to change your car’s transmission fluid yourself, then it’s typically a “drain and fill” type of job. You’ll first need to locate the “drain” and “fill” plugs on the transmission and undo the “fill” plug first. The reason for this is that if you drain the transmission and the “fill” plug is stuck, you won’t be able to fill it in the end.

When pulling the drain plug, you might notice that a small amount of fluid comes out. Amsoil reports that this is due to about two-thirds of the transmission fluid remaining in other parts of the transmission, like the torque converter. As such, it’s important to change the fluid regularly in order to get all of the debris and dirty fluid out over time.

If you don’t want to wait for all of the fluid to be clean, then you can do a flush instead. A full fluid flush will require a special machine that hooks up to the transmission lines in order to pump new fluid in and flush out the dirty fluid entirely. While it can clean up the transmission internals better than a simple fluid change, keep in mind that a proper flush could cost you anywhere between $100 and $150, depending on the car.

Can changing the car’s transmission fluid damage it?

No. If anything, changing a car’s transmission fluid will prolong the life of the transmission and keep the car running longer. If you don’t change the transmission fluid regularly, if not at all, then you run the risk of the transmission being damaged. Also, it’s important to use the correct transmission fluid for your specific application. So be sure to check the owner’s manual for the right one.

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