Can A Transmission Go Bad From Sitting For A Long Time?

If you had a car sit for a while or if you are buying a car that has been sitting for a while, there are some things you should know when it comes to the transmission. We talk a lot about transmission problems on lifeonfour, so this topic has been on our minds for a while. We will reveal what exactly can go bad on a gearbox that has been sitting for an extended period of time. Stay with us!

What damage can you expect on a transmission that was sitting for a long time?

There are a number of things that can potentially go wrong with a transmission that has been sitting for a while. It depends on the amount of time gearbox or a car has been sitting parked. If we are talking about shorter periods of time (less than 6 months), you should not expect any problems. As soon as we extend that time frame to more than a year is when we would start getting cautious or even recommend some preventive fluid changes. Longer periods of time (2 and more years) are considered to be an area where certain components can start failing, leaks start forming and so on. 

Transmission fluid – does it go bad?

The first question you might be asking yourself about any gearbox that has been sitting for a while is probably related to how is that fluid keeping up? This is a hot topic. Literally, a debate on the shelf life of engine oils and transmission oils is a hot one. Certain engine oil companies claim that the shelf life of their oil is no longer than 3 years in a perfectly sealed bottle. Many other companies however claim that the shelf life of engine and transmission fluids is not something you should worry about. 

We tend to lean towards the side of those short-shelf life companies. Every fluid in your car is subject to two wear-related factors: friction and time. Yes, we all know that transmission fluid breaks down over time with heat, friction, pollutants and time. But ask any old mechanic and they will gladly tell you that engine oil and transmission fluid also go bad even with just time. Time-related degradation of viscous properties is a real thing which is why we recommend that every transmission that has spent more than 1-2 years sitting in a garage should have its old transmission fluid replaced. Read more about transmission fluid degradation.

Transmission gaskets and seals

Transmission gaskets and seals are (usually) made out of thin rubber. As the transmission sits, rubber materials eventually start breaking down. They usually break down faster if the car is used on a daily basis due to the changes in temperature and pressure but these rubber gaskets also break down with time passing alone. Aging rubber that starts breaking down, eventually leads to leaks of transmission fluid. This process is sped up if the transmission is sitting outside where the temperature varies from extreme cold to extreme heat.

Clutch drum and internal clutches

This third reason why an automatic transmission can go bad from sitting is a bit more complicated. In rare cases, a clutch drum can seize or go bad as the transmission sits parked for a longer period. The same goes for the internal clutches of the automatic transmission. Internal clutches can get stuck together which prevents the car from shifting up or down or it can lead to hard shifting

We will explain how you should start and drive a transmission that has been sitting if the internal clutches have glued together during this time. Read more about automatic gearbox clutches.

How to inspect and drive a transmission that has been sitting for a while?

In this section, we want to do a step-by-step guide on how to inspect and drive with a transmission that has not been driven in some time. If you feel as though you are not competent enough to go through this process on your own, make sure a mechanic is present.

  1. Inspect the outside of the transmission
    Inspecting the outside of the transmission can reveal a lot, especially about the state of gaskets. Any oil leaks are easily spotted immediately and they should not be ignored.
  2. Check the transmission fluid level and state of transmission fluid
    If you happen to discover any oil leaks, make sure you check the transmission fluid level before even thinking about turning on the car. Long-term leaks, even small gasket leaks can completely drain the transmission of fluid. After you check the level of transmission fluid, make sure you also visually inspect the transmission fluid. Healthy transmission fluid should be transparent with a certain shade of color (red, green, purple, etc. depending on the make of the fluid). Worn out transmission fluid is usually completely black and thick.
  3. Start the car and take it easy
    After you make sure that the transmission is full of fluid that is not completely watery and black, turn on the engine and move the shifter from Park to Drive a few times with 5-second pauses in between each shift. This gets the fluid pumping and circling around the transmission and it also helps with stuck internal clutches and seized clutch drum.
  4. Go for a relaxed 5-mile drive
    If you feel the transmission pulling as it should, it is a good sign that everything is in working order. Go for a relaxed drive and observe how the transmission is behaving. If there are any signs of issues (which we listed here), stop driving until the problem is diagnosed and resolved.
  5. Drive and maintain it regularly
    If everything is in perfect working condition, which is most of the time, enjoy the car and drive. We still recommend flushing and replacing the transmission fluid if you don’t know when it was last replaced. This includes the filter. The cost of transmission fluid and transmission filter replacement is minuscule compared to the list of benefits of new transmission fluid. Remember, preventive maintenance is the key when it comes to any kind of transmission.

Does changing transmission fluid improve transmission performance?

Yes, flushing and replacing the transmission fluid and filter do greatly improve the performance of your transmission. The internal parts of every automatic transmission are lubricated and cooled by a constant flow of transmission fluid. As the transmission fluid breaks down and becomes less viscous, there is more friction in the transmission, more mechanical wear and more pollution in the form of microscopic metallic shavings that clog the transmission fluid filter. 

Fresh transmission fluid will make your transmission shift smoothly and it will keep it smooth and running for years to come.


Having a transmission sit will not make it bad, it will however suffer some damage that is time-related. There should not be any new mechanical internal damage if it was not present before, however, a sitting transmission can develop transmission fluid leaks and the transmission fluid inside the transmission should be replaced if it’s old. All the advice we listed above is true for both hydraulic automatic, CVT, DSG and manual transmissions.

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