This is why the transmission slips after a fluid change

To answer the question, after a transmission fluid change, many drivers expect their transmission to function better instead of worse.

Yet, this is not always the case. Based on the condition of the transmission and what is going on inside, some transmissions begin to slip. And, there are several common reasons why, including the following:

  • Varnish deposits
  • Wrong Type of Transmission Fluid
  • Problems with the Components

With that being said, here are a few things that every driver needs to know about problems with the transmission slipping after a fluid change.

Causes why transmission may slip after changing the fluid

As referenced above, there are several reasons why your transmission may slip after the fluid has been changed. These are common problems that all drivers need to pay close attention to before having these services performed on their vehicles.

1. Varnish Deposits Floating Around

Sometimes the vehicle owner may not change the transmission fluid on a regularly scheduled basis. Unfortunately, whenever this happens, they may wait too long to have these services performed.

By the car owner waiting longer than they should, the transmission fluid in the car may not only be old, burnt, and discolored, it usually results in varnish deposits floating around inside the old transmission fluid.

However, once the old transmission fluid is replaced with a new transmission fluid, these left back deposits will stick to the filters inside the transmission system.

And, as the build-up of these deposits begins to form, they can prevent the new fluid from flowing freely through the transmission. This is also why a fluid change can lead to the transmission slipping.

2. Transmission Fluid is the Wrong Type

Before replacing the transmission fluid in any vehicle, it is best to read the owner’s manual. It will note where the vehicle requires Mercon or Dextron transmission fluid. By doing your homework in advance, you can avoid using the wrong type of fluid.

On the other hand, if you do not use the right type of fluid, it can lead to unnecessary problems like transmission slipping. Just like old burnt fluid can leave back varnish deposits, the same problems occur when the wrong type of fluid is used.

3. Problems with Undetected Bad Components

In some cases, the components in the transmission may be old, worn, or not properly functioning. Yet, these problems may go without being detected until after the fluid has been changed.

Can the transmission be damaged by changing the transmission fluid?

The answer to this question usually varies based on the circumstances surrounding the change in transmission fluid. For instance, if someone uses the wrong fluid in their vehicle, it may cause several problems to the transmission system, including poor lubrication, overheating, and the potential for transmission failure.

However, whenever this happens, a mechanic may be able to reverse this damage by flushing out the bad fluids.

How do you fix a slipping transmission?

If the transmission begins to slip after a fluid change, the problem needs to be addressed right away. Fortunately, there is most likely a simple fix for these types of issues.

For instance, if the problem is due to varnish deposits preventing the new fluid from flowing properly through the transmission system, you can do a transmission flush to force the new fluids through.

How long does it take for a new transmission fluid to work?

According to the information posted by MechanicAdvice, the timing for the new transmission fluid to work can differ. However, after you have turned on the car and have shifted into drive, it will only take about 5 to 10 seconds for the new fluid to circulate throughout the entire system.


Why is the transmission slipping after a fluid change? The answer to this question is usually based on the situation that has occurred.

However, when a mechanic inspects the vehicle, they may find one of several common reasons, including varnish deposits sticking to the filter, or the wrong type of transmission fluid used when these services are performed.

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