Will a Transmission Flush Hurt My Car or Make It Better?

Will a transmission flush hurt my car?” when it’s time to change the fluid or observe some mishaps in the car’s gearbox. They think that, like an engine, the transmission needs regular fluid changes to work efficiently.

Will a Transmission Flush Hurt My Car or Make It Better

Interestingly, some professionals warn against flushing a transmission while others encourage the practice. We’ll settle the confusion and discuss the possibilities and advantages of both scenarios in this article.

Will a Transmission Flush Hurt Your Car?

No, a transmission flush won’t hurt your car. Rather, it enhances its efficiency and performance. It is especially useful when air bubbles form in the fluid or when you need to change any of the components in the gearbox. Aside from that, you don’t need to change it regularly.

A transmission fluid change, when done properly, won’t damage the gearbox. However, transmission problems crop up when the flush is poorly done. A poorly done flush allows air bubbles and debris into the system, which won’t augur well for the gearbox.


Also, most people only do transmission flushing after they notice gearbox problems, and by then, several components in the car are already damaged. Some of these damaged components may escape the driver’s notice before the transmission flush and might only notice it after. This gives the impression that the flush caused the damage. Thus, the driver draws the conclusion that the damage was a result of the transmission fluid change.

Why Do Mechanics Discourage Transmission Flushes?

Mechanics discourage transmission flushes because it puts the transmission at risk of damage. It is one of the easiest ways by which air and debris get into the system. A transmission flush can also damage aging seals and cause a slipping clutch.

Transmission Flush Puts the Transmission at Risk

A flushing process may generate eddy currents, forcing the fluid to move in the wrong direction of normal flow. Thus, the fluid dislodges debris and sends it to where it shouldn’t be. Usually, the flushing process is designed to “wash away” debris or air bubbles out of the system. However, instead of the debris flowing out, it flows against the current and ends up back in the system.

Automated Car Transmission Fluid Draining

Debris can cause the gearbox to fail or make it harder to shift the gears. It can also contaminate the fluid and cause the gears to slip. Air bubbles can also cause overheating by blocking the smooth flow of the fluid throughout the transmission. They can disrupt the work of solenoids, actuators and valves, preventing them from connecting with clutch packs and drums.

Transmission Flush Damages Old Seals

A transmission flush can damage old seals during the process due to the force exerted by the machine. What happens is that you’re forcing old fluid out of the system and replacing it with new fluid simultaneously. The aging seals may not have the capacity to withstand the force coming from the liquid, causing them to crack.

Mechanic Try to Stop Transmission From Draining

Damaged seals will cause leaks in the system, allowing the fluid to flow into other areas of the system. This leads to leaks in the transmission, which causes hard shifting, as the fluid won’t be enough to lubricate the system. Transmission leaks also lead to overheating, throwing up the check engine light, and resulting in slipping gears. They can reduce acceleration and gearbox efficiency due to inadequate fluid in the system.

The Difference Between a Transmission Flush and a Fluid Change

The difference between a transmission flush and a fluid change is that a flush requires a machine that draws out the old fluid while pumping in a new one. It is usually done by a professional. On the other hand, transmission fluid change doesn’t require any machine.

The flushing process involves removing all of the fluid in the transmission, which can be dangerous. However, the transmission change requires removing fluid from the pan, changing the oil filter and adding new fluid. Unlike the flushing process, you don’t need to draw out all the fluid in the transmission. Thus, flushing the transmission is more thorough and efficient compared to changing the fluid during a transmission service.

Flushing the transmission dislodges debris, which is risky as the debris could block passages in the transmission and damage it. However, changing the transmission fluid involves little risk as there’s no dislodging of debris. The cost of transmission flush is higher than changing the fluid due to the tools required, the time spent and the energy expended. To change transmission fluid is a simple process that requires fewer tools, time and energy.

How to Determine If Your Car Needs a Transmission Flush

Determining whether your car needs a transmission flush depends on several factors, including instructions in the car manual, fluid color and odor. Other factors are the fluid level, fluid consistency, stress on the transmission, gearbox problems, mileage and driving conditions. Ensure you do proper checks before flushing the transmission.

Instructions in the Car Manual

First, check your car’s manual for instructions on how to go about flushing the transmission and what tools you’ll need. The manual also contains recommendations on the correct intervals between maintenance schedules. It’ll tell you how long or far your vehicle should run before you do the flushing procedure. It’ll even inform you when to change the transmission fluid.

Couple Reading Car_s Manual

Some car manuals even insist that their vehicles don’t need to be flushed based on a few safety measures they’ve put in place. Car manuals also give hints of the symptoms you should see before flushing and tell you where you can take the car for the procedure.

Thus, refer to your car manual before attempting to flush the transmission to be abreast with the entire process. Failure to do so may endanger your car’s transmission because all transmissions are unique and need specific care.

The Level of Fluid

The transmission fluid must be of a specific volume or level to work efficiently. If it isn’t, the transmission’s moving parts won’t be well-lubricated, causing them to rub against each other. Eventually, the system will break down and might need flushing instead of merely changing the fluid. The transmission system is airtight, meaning no fluid can come out except if there’s a fluid leak in the system.

Once there’s a leakage, debris can get into and damage the system. The best way to get rid of debris is by flushing the system instead of merely changing the fluid. Thus, the level of fluid will determine whether your system needs a flush or not.

However, don’t just rush to flush your system because there’s a leak; consider other factors as well before drawing a conclusion. To avoid this, never do a transmission flush without filter change.

Change in Color and Odor of the Fluid

You should also consider a color change or fluid odor before settling for a flush. Transmission fluids are usually dark reddish or pinkish. Over time, the color becomes darker due to continuous use, so don’t be alarmed. However, when the color changes to dark brown or black, you should be worried because you have a dirty transmission fluid.

Technician Working On Car_s Transmission

The color is affected by wear and tear in the transmission as well as dirt outside the vehicle. The transmission is made up of moving parts that are lubricated by the fluid. As time goes on, the liquid loses consistency, causing the parts to grind against each other. The grinding action releases specs of debris into the fluid and changes its color.

Aside from the color, you can tell your system needs a flush from the smell of the fluid. If the fluid has a burnt smell, it’s an indication that the transmission is overheating. Overheating comes about when the fluid breaks down and can no longer cool the transmission. The breakdown of the fluid increases friction, which results in a burnt smell.

When the Gearbox Develops Problems

One cardinal sign that your vehicle needs a flush is when your gearbox develops problems. If your transmission fluid is fairly new, but the gears are hard to shift or they slip, then you should consider flushing.

Pieces of Car_s Gearbox in Hands Of a Mechanic

If you experience rough shifting or hear near noises in the transmission when you drive, then the gearbox is faulty. Other signs include jerking, delayed engagement, and shaking while the gear is in neutral.

Mileage and Stress on the Transmission

This indicator is common in manual transmissions, though automatic transmissions also undergo stress. If you join long traffic queues to and from work and need to change gears quite often, you put a lot of stress on the transmission. Also, towing trailers and driving in hilly areas stresses the transmission; thus, it requires a regular fluid flush than the average one.

Mileage is also a good sign that you have to flush your transmission. For example, if the manual recommends flushing the transmission every 50,000 miles, doing otherwise may hurt the system. Thus, once you hit or surpass that mark, you have to flush to ensure your transmission stays in prime condition. It is bad to go 300,000 miles never changed transmission fluid.


So far, we’ve answered the question of whether a transmission fluid flush will hurt your car, the differences between a flush and fluid change, and the signs you need a transmission flush.

Here’s a summary of all that we’ve discussed:

  • When it’s done properly, a transmission flush won’t hurt your vehicle but enhance its efficiency and performance.
  • A transmission flush is not the same as a fluid change because the former requires a machine and can be done by experts.
  • On the other hand, you can perform a fluid change yourself without the help of any machine, and you don’t need to draw out all the fluid.
  • Since transmission flush isn’t child’s play, you should look out for signs that the transmission needs a flush before undertaking one.
  • One major sign is when you have gearbox problems after transmission fluid change, while another is when the fluid color changes.

If you begin to perceive a burnt smell coming from the transmission or the level of fluid drops drastically, it may be time for a flush. Thus, if you’re wondering, “Should I get a transmission flush or change?” look out for these symptoms.

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