Transmission fluid is required in engines to provide proper lubrication and hydraulic pressure to internal moving parts. You may notice the transmission fluid level dropping and wonder if it evaporates in the engine. So, in other words, no, the transmission fluid does not evaporate.

Transmission fluid is present in the transmission oil pan in the engine compartment. This transmission oil pan is an airtight container, so no air can get in or out of it. As a result, no condensation can occur in the transmission fluid.

Why does the transmission fluid not evaporate?

Because the transmission pan is airtight, the transmission fluid does not evaporate, and the fluid level does not decrease. When the transmission fluid is stored in the transmission oil pan, evaporation begins due to the dry air in the container. 

However, as the air becomes fully saturated (100% humidity), evaporation stops completely because the liquid vapors have nowhere to escape. This is why, even at high temperatures, transmission fluid does not burn. 

So there could be another reason why your transmission fluid is running low.

Can a car lose transmission fluid without a leak?

As we know, transmission fluid does not evaporate or burn away. The only way for the transmission fluid level to drop is if there is a leak. 

The color of the transmission fluid is reddish or brownish. When there is no visible evidence of transmission fluid leaking, people believe the fluid is evaporating. There is a chance that the fluid is leaking in such small quantities that it is not visible, but this does not mean that there is no problem.

This leakage can occur when transmission fluid parts become corroded, clogged, or damaged. Transmission fluid levels in engines can drop for various reasons, including corrosion in the transmission pan or a leak in the transmission drain plug. Let us investigate further.

Why is my transmission fluid disappearing?

Because transmission fluid can leak, it can cause serious damage to the engine. It is critical to recognize the symptoms of low transmission fluid in the engine and diagnose the problem as soon as possible.

The following are some indicators that the transmission fluid level is low:

  1. When you shift gears or accelerate the vehicle, you may hear a grinding noise from the engine. Shifting gears can also be difficult if the transmission fluid level is low. If you think low engine oil has an effect on transmission, that’s incorrect.
  2. The clutch is not functioning properly. If the transmission fluid level in the engine is low, the clutch will not operate smoothly.
  3. When new, transmission fluid is bright red; when old, it turns a dark brown color. If your transmission fluid leaks, you may notice red or brown patches beneath your car or on engine parts.

Causes of Decrease in Transmission Fluid Levels

  1. A worn-out rubber gasket can cause transmission fluid leaks in the engine.
  2. Transmission drain plug seals that are faulty can allow fluid to leak out.
  3. The transmission’s ventilation system can become clogged over time, causing the transmission fluid level to drop.
  4. Corrosion in transmission fluid pipes can cause fluid leakage.
  5. Corrosion can cause a dent or crack in the transmission fluid pan. Any dent or damage to the transmission fluid pan can cause the fluid to leak from the engine.

FAQ’s on Does Transmission Fluid Evaporate

The cost is entirely dependent on the cause of the transmission fluid leak.

If the transmission pan is damaged, it can cost between $1,500 and $3,500. If the transmission drain plug causes the leak, you can easily replace it for about $10. Replacing the seals or gaskets can cost between $300 and $600, including labor.

You should contact your mechanic for a more accurate estimate of the cost of repairing the transmission fluid leak.

Yes, the transmission seals dry out when the car sits for an extended period. Modern vehicles contain additives that prevent the seals from drying out when the car is not driven for an extended period.

But still, It is recommended that you drive the vehicle once every 2-3 weeks to ensure that the transmission fluid is properly circulated in all moving parts.


So we learned that transmission fluid does not evaporate. The only reason the transmission fluid is running low is because of leaks. A crack in the pan, a loose drain plug, or faulty gaskets in the transmission can cause transmission leaks. 

Low transmission fluid levels can cause hard clutch movement, difficult gear shifts, and engine grinding noises. Make sure to contact the mechanic as soon as possible to leak repaired.

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