Symptoms of Too Much Transmission Fluid

Do you ever wonder what makes your car’s transmission function as seamlessly as it does?

The secret lies in the transmission fluid.

This multipurpose liquid performs several different functions. It facilitates gear shifts by ensuring all moving parts of the transmission remain lubricated.

It reduces heat caused by friction to keep the overall transmission system cool.

The quality of your transmission fluid deteriorates over time.

Therefore, it is recommended that you check it regularly in order to avoid the potential for internal wear.

Signs of discoloration or a burnt color indicates it’s time to replace your transmission fluid.

What happens when you use too much transmission fluid?

Overfilled transmission is our main concern today because it seems many car owners are faced with this predicament.

Symptoms of Too Much Transmission Fluid


Humming or whining noises are associated with the transmission. These noises indicate a couple of issues that may be difficult to differentiate.

Transmission whine is one of the most misleading symptoms of all and has caused many drivers to pay for needless service. A certain amount of whine is normal.

Whining noise suggests that there’s a transmission fluid pump problem that could be due to overfilling or low-level fluid.

The transmission can generate an irritating humming noise often linked to excess fluid in the transmission.

Over Heated Engine

When filling the transmission in a hot engine, the transmission fluid will become heated. When any liquid is heated, it will expand in volume.

Therefore, there must be enough space in the transmission for the hot fluid to expand.

If the engine is not hot, there is a higher possibility of overfilling the transmission, since the cold fluid will not expand.

Excess transmission fluid will result in an overheated engine and possible transmission problems.

Leaking Transmission Fluid

Your engine loses a metered amount of oil after a certain number of miles, but the fluid in the transmission should stay put at the ideal level.

Too much transmission fluid in the car will not break the seals; however, the excess will leak. Usually, the transmission has a venting system that helps to prevent pressure buildup.

Excess fluid in the transmission can leak through the vents, resulting into leakages. Leakages may also occur in the seals that are found higher in the transmission.

Aerated Transmission Fluid

A fluid level that is too high will cause the fluid to become aerated. Aeration is the direct combination of air with the transmission fluid, which causes bubbles.

Aeration can lead to a loss of converter efficiency and burned out clutches. The aerated fluid will lose viscosity and becomes less effective as a lubricant.

Overall, aerated fluid in the transmission can cause poor lubrication, overheating, irregular shifting, and converter aeration.

Slipping Transmission

A transmission that does not upshift to direct drive within a normal speed limit must be faulty. The system must be suffering from slipping.

Usually, slipping becomes apparent when the engine speed runs away before the transmission upshifts.

The usual causes of slipping are low fluid level, burnt fluid, torque converter problems, solenoid issues, worn-out gears, and worn/broken bands.

However, overfilled transmission fluid slipping is most likely to occur if you overfill your transmission.

How to Fix Overfilled Transmission

There is but one way you can fix this problem. You need to check the fluid level when filling. This way, you can easily avoid overfilling.

First, and for most, you should know that the fluid level rises typically as the fluid temperature increases.

As such, you should not check the level before the transmission has reached normal operating temperature.

Automatic transmission fluid level is usually checked with the engine running. In this case, the transmission has to be in a specified gear position.

Most fluid levels in the transmission are checked with the transmission in park, while some transmissions can be checked in neutral.

The dipstick is found behind the engine, which fits into a large round tube.

When you are reading the fluid on the dipstick, know that the add mark denotes measurement unit.

It is of utmost importance that you follow the correct procedure when checking the fluid level. The incorrect procedure may result into overfilling.

Correct Procedure to Follow

  • The transmission should be at normal operating temperature
  • Park the car on a level surface, then turn off the engine and open the hood
  • Wait at least twenty minutes after the engine shuts down
  • Withdraw the dipstick and wipe it clean using a lint-free wiper and insert it fully. Once you remove the transmission dipstick, you will notice it has gradual marks on it indicating where the fluid level should be located.
  • Withdraw the dipstick and read the fluid level on both sides to determine the actual transmission level.
  • The fluid level should be maintained within the crosshatch area of the dipstick by adding fluid as needed.
  • The lower end of the crosshatch is normally the minimum fluid level, while the upper end of the crosshatch indicates the maximum fluid level.

How Much Transmission Fluid Goes in a Car?

The transmission requires the ideal amount of fluid in order for it to function properly. Overfilling because you don’t know the ideal amount is not an option.

The good thing is that every automobile has a specification for the correct amount of transmission fluid.

A great number of passenger automobiles take 12 to 16 quarts of fluid.

However, the model of the automobile determines the type as well as the amount.

You would expect all vehicles to come with a dipstick, but there are certain models that do not come with a transmission dipstick.

With such models, you will have to lift the levelly and then check the fluid from under the car.

Do not continue to add fluid because of leakages. If the cause of the leak is not overfilled transmission, you should have the car checked by a professional.

When filling the transmission, you should always allow time for the fluid to drain to the bottom of the transmission, then recheck the level to make sure that you are not overfilling.

Jason Hennessey

I have lived and breathed the automotive sector for over 7 years. As a taxi driver, fleet owner, garage services provider, I have gained the knowledge and passion for providing a service that is fair for everyone involved in the ride-hailing industry.

Leave a Comment