Car Oils And Fluids

Can Changing Transmission Fluid Be Bad For Your Transmission?

Mike Cross
Updated Oct 17, 2020

Outside of your engine, the next biggest component of your car is the transmission. Like the engine and the oil it has the transmission has its own fluid. That fluid is called transmission fluid. In this article, we will look at if changing your transmission fluid can be bad for your transmission.

We will cover the different kinds of changes with transmission fluid and also why it might possibly be bad or why you have might have heard that it is bad. Read on to learn everything you need to know about your transmission and transmission fluid.

Can changing transmission fluid be bad for your transmission?

What is Transmission Fluid?

Before getting into changing of transmission fluid and if it is bad or not we will briefly cover what transmission fluid is. In simple terms transmission fluid is the oil for your transmission.

Transmissions have over 800 moving parts, and these parts need to remain cool and lubricated to work properly. That is what the transmission fluid does.

Transmission fluid, however, lasts a lot longer than engine oil. A lot of car manufacturers will rate their transmission fluid for over 100,000 miles; this makes it hard to know if you should change it or not.

How to Know When to Change?

The best way to know if your transmission fluid is needing to be changed or not is to look at it. It should be a reddish color, and if it still is, then it is probably good.

If it is black, then it is burnt and needs replaced. If it is starting to get dark, but still has some red tinge to it, then that is the perfect time to replace it.

Options for Replacing

You actually have a couple of options when it comes to changing transmission fluid, and that is having your transmission completely flushed or just changed.

This is where the real debate lies for if it is bad for your vehicle or not.

Transmission change

A transmission fluid change is the simpler of the two options. With a transmission fluid change, the transmission fluid is drained out of the pan, and the filter is changed. The transmission pan actually doesn’t hold that much fluid in it tough.

On most vehicles, it holds about half the fluid, but the other half is still inside the torque converter and lines. When doing a transmission change, you are only replacing about half of the old fluid. This will get important later on explaining why transmission fluid changes might be bad.

Transmission Flush

A transmission flush, on the other hand, removes all the fluid or tries its best too. The pan is drained, and then a machine is hooked up to the cooler line, and it pumps out all the rest of the fluid.

This removes 95% of the fluid and also the gunk that comes with it. Then the new fluid is put in. This way makes the fluid brand new which logically seems better, but is it?

Why can Transmission Flush be Bad?

Why can transmission flush be bad
Why can transmission flush be bad?

If you are reading this, then you have probably heard stories where people have had their transmission flushed, and then it stopped working.

If people didn’t have problems with their transmission after fluid changes, then there wouldn’t be the question of if a transmission fluid change is bad or not. So, now we will get into why it might be bad now that you understand the two ways of changing transmission fluid.

When transmission fluid gets old gunk builds up in it. Pieces of the gears break down and get in the material. These extra pieces get between the gears in the gearbox and make gaps. As long as the metal is there, then the gears will work fine, but if they are removed, then you might start getting slipping.

This is why some people think that flushing the transmission and removing all the gunk can be bad and hurt it and why you hear stories of people getting flushes have their transmission stop working.

Is the Flush to Blame?

Is, the transmission fluid flush really to blame though? The answer is no; the blame is that the transmission wasn’t taken proper care of to start with.

If you take proper care of your transmission and have the fluid changed or flushed regularly, then you won’t have to worry about components breaking off into the fluid and for gaps occurring. Proper transmission care will keep your transmission working correctly.

Should You Get a Flush or Change?

With that said, should you get a transmission fluid flush or just a change? Well, the answer is it depends.

If the car has always been yours, then you can get the transmission fluid flushed and not have to worry about anything because you know how often and how well you took care of it.

However, if you have not always had the vehicle and it has a lot of miles on it, then you should probably just start having the transmission fluid changed when it is needed.

That way you don’t have to worry about the free metal being removed. This will make sure your transmission will keep working, even if it won’t last as long as a properly taken care of transmission. If the car is yours, you should have the best battery tender for car to recharge your battery. It will improve the life of the battery.

The Key

The key thing with your transmission though, and making sure a flush won’t hurt your transmission is to stay on top of the fluid that is in it. You want to care for your transmission from the life of it, so you don’t have to worry about pieces breaking off.

You can do this by having the fluid changed based on what your mechanic recommends and having it flushed every other time or so.

Also, you need to stay on top of your fluid level and make sure it isn’t getting old and burnt. Some people will say don’t bother it till you have problems, but once you have problems fixing them is expensive.


So, to wrap things up is changing the transmission fluid bad for your transmission? The answer is no, changing the fluid is never bad for your transmission. A change only removes about half the liquid anyways.

Is a transmission flush bad for your transmission then? Well, the answer to that is also no. A flush is never the thing that is bad. If your transmission is damaged already though, then a flush can cause the problems to start showing, but the thing that was bad was the improper care of the transmission, to begin with.

Should you have your fluid flushed? The answer to that is it depends. If you have always had the car and took care of the transmission, then a flush is fine.

If you haven’t always had the vehicle through and it has a lot of miles, then I would just stick with transmission fluid changes, that way you don’t have to worry about possible problems showing up.

Now you know enough though to make an informed decision on if a transmission flush or change is right for you and you also know the answer to the question of is a transmission fluid change bad for your transmission.

Mike Cross
Life is too short to drive with stock audio

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