Does changing transmission fluid help shifting? 

(Last Updated On: August 28, 2023)

Shifting or changing gear can become problematic at any time. But can something as simple as changing the transmission fluid cure the issue?

The thing to note with transmission fluid differs massively from engine oil. Transmissions do not operate at the same high temperatures as engine oil, so a simple change doesn’t have the same effect as an engine oil change on the vehicle’s driveability. The issue with transmission oil, which can help with shifting when changed in certain circumstances, is that the debris needs to be removed from the gearbox. Debris can only be removed from the transmission when the old fluid is removed.

Can changing transmission fluid help shifting?

It may not be the answer you were looking for, but changing the transmission fluid on a manual gearbox will not help with shifting. If the fluid level is between the minimum and maximum level on the gearbox dipstick, and there are no leaks, then changing the fluid will not improve shifting or fix a car stuck in gear

Transmission fluid only lubricates all of the components inside the transmission. It has no bearing on the smoothness of the gear changes. It will only make a difference if the transmission fluid is excessively low. You can read more about driving on low transmission fluid here.  

If you experience shifting issues on a manual transmission and the level is still correct, then be aware changing the fluid may not solve the problem. Changing the gearbox fluid will not fix the following issues: 

-Crunching noises when shifting  

Leaking transmission fluid

-Clutch problems such as a slipping clutch

-missing gears

car jumping out of gear

If the reason you found your way here is any of the above issues, unfortunately, your car needs a visit to the garage for a more serious repair. 

Will changing dirty transmission fluid improve shifting in an automatic?

Changing dirty fluid may improve shifting because automatic transmissions work very differently from manual.

The solenoids that the signal to change gear comes too open and allow transmission fluid through a plunger—putting pressure on the clutch and transmission to change gear. Dirty transmission fluid could cause the shift solenoid to stick open or shut, resulting in shifting issues. A simple transmission fluid flush will probably not be enough to solve this problem. It’s important to understand that changing the automatic gearbox’s transmission fluid is much more critical than a manual. 

How often should you change transmission fluid?  

Changing the transmission fluid is part of the vehicle service schedule. Vehicle dependent, this is anything from 30,000 to 60,000 miles. 

If you don’t drive enough to reach the mileage, you could consider changing it between 3 and 5 years. 

Although, changing the transmission fluid will not improve shifting. When changing the fluid, the debris can be removed from the gearbox. A gearbox is a sealed unit, so you may wonder how debris can get in. 

Well, tiny metal particles from gears are shaved and crunched away over time. You aren’t doing anything wrong. A gearbox always has two metal components in contact with each other, these gears will wear out, and the metal has nowhere to go until removed. 

The reason for changing the fluid in the first place is to relubricate the touching gears and keep them in the best shape for as long as possible. 

Should you change the transmission fluid if it has never been changed?

During an annual service, the garage will highlight when the transmission fluid next needs changing, if not already due. If you’re purchasing a second-hand vehicle and there is no evidence of a change, consider a flush for peace of mind. Changing the transmission fluid is inexpensive and will help prolong the life of the transmission’s internal components.

It shouldn’t take your garage more than an hour to complete a transmission fluid flush from start to finish. 

What happens if you don’t change the transmission fluid? 

If you ignore a transmission change, the fluid becomes worn and stops acting as a lubricant. In a manual vehicle, although damage probably won’t be done for a considerable time, the dirt and the debris built up in the transmission will wear the components out.

In an automatic transmission, the fluid acts as a lubricant and a hydraulic fluid. The worn-out debris floating around the transmission will be passed through components, gaskets, seals, etc. A much more sensitive system that a small amount of debris could damage.

Final thoughts

Changing the transmission is part of a vehicle’s standard service schedule and shouldn’t be ignored throughout the car’s life.

To summarise, does changing the transmission fluid help with shifting? The answer is no. Only changing or topping up the fluid due to very low fluid improves shifting if that is the cause. 

My name is Tom although my friends call me Tommy. Messing around with cars and bikes has always been a hobby of mine even from a young age. So I made it my day job 17 years ago. I am a fully qualified mechanic as you would expect. I've worked in all different areas of the motor trade, valeting, panel beating, engine repairs, I'm sure you get the idea. I enjoy sharing my wealth of knowledge and experience with others, which is the reason I spend a lot of time here writing for this website.

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