What Are the Signs and Repercussions of Too Much Transmission Fluid?


Transmission oil, unlike engine oil, is not only a lubricant but also serves the purpose of both oil and hydraulic fluid. The fluid or oil helps in reducing the heat caused by friction and keeps the transmission system at a cool temperature. It also facilitates gear shifts by ensuring every part of the transmission is well-lubricated. However, the performance of the fluid can deteriorate over time, and it is essential to monitor it regularly to avoid any internal damages.

Overloading any automobile with excessive transmission fluid is not a suitable choice, many vehicle owners overlook this factor, or lack of adequate information regarding transmission oil can cause damage to the transmission system over-time. Therefore, automobile companies have worked deliberately to provide guidelines for the right amount of oil usage.

In this article, we will discuss the signs, consequences, and precautions you need to take with your car’s transmission fluids for the prolonged well-being of your vehicle.


Evident Signs Of Excessive Transmission Oil

Transmission fluid is the mainstay of any transmission system, and the slightest of carelessness to maintain the fluid levels can be very harmful to the vehicle. It is tricky to determine if you have overfilled the transmission system or not.

However, here are a few signs that can indicate if there are any issues with your vehicle’s transmission fluid levels.

1. Unusual Sounds In The Transmission System 

An Engine’s sound can over-power the transmission sound, as they are closely integrated, it can be difficult to distinguish where the sound is coming from. This can be a major reason why vehicle owners overlook the damage in the transmission system. Grinding, humming, and whining are a few prominent sounds that indicate complications in the transmission system.

Whining Sounds

Whining sound is a sign of overfilled or low-levels of fluid in the system; it suggests there’s a problem in the transmission fluid pump.

However, whining sound can be a little misleading, as a little whining in the system is normal, but if it’s a blaring sound, you need to attend to these sounds immediately to avoid extra expense at the time of the car servicing.

Humming Sounds

Humming in the system is another signal of excessive transmission oil, it’s a very mellow yet sharp sound and can be heard within a few minutes after the engine is completely warmed up.

Grinding Sounds

Grinding, on the other hand, can be due to a lot of other maladjustments in the system. However, it can be a noticeable cue that breaks are rubbing against each other, and that can be due to quantity fluctuation of the transmission fluid in the vehicle.

2. Dripping Transmission Oil

Engine consumes a certain amount of oil after a specific number of miles, but the fluid in the transmission should persist on an ideal-level. Though the transmission system has venting-frames, which can eliminate the pressure build-up in the system, excessive fluids can crack these frames, causing leakage.

Locating the Oil Drips

The oil drips can be located right under the transmission system. The color of these oil stains is reddish, a great way to differentiate from other oil leakages. Though it’s an indication of excess fluid in the system, there can be other reasons also as to why there is a fluid leakage through the venting-frames. Blindly believing leakage to be the sole reason for fluid overflow is not advised.

3. Drift In The Transmission System.

If a transmission system is causing a delay in the up-shift of the gearbox within the normal speed limit, it is drifting from performing its designated functions. Usually, drifting or slipping of the system is evident when the engine picks-up speed before the transmission system could help the gearbox to ascend to a higher level.

Cause of Drifting

This drifting is mostly caused by low-levels of fluid, worn-out breaks, excessively burnt fluid, and an overabundance of transmission fluid in the system. All the mentioned deformities can delay in foam creation, damaging the seals and resulting in leakage, ultimately delaying the transmission system’s functioning.

4. Overloaded “Dipstick”

Unfortunately, not every car model is installed with the “dipstick,” but it can be a helpful indicator in preloaded car models. However, it is not the most reliable method but can give you a fair idea of elevated levels of the fluid inside the system. The dipstick is doubted for its accuracy purely because of the fluctuation in the oil consistency.

Oil consistency in a running transmission is fragile and can instantly become thick with a modest drop in the temperature. It is always advised to check the dipstick levels only after running the engine for a certain time. Certain issues have also been noticed with the inner wall of the dipstick port, oil tends to stick to it, again causing an inaccurate reading.

Though it cannot be trusted completely, dipstick can give you an overview of the oil levels in the transmission.


Repercussions Of Overloading The Transmission Oil

After understanding the basic indicators, it is also important to acknowledge what can be the ultimate consequences of overloading the system with the transmission oil. As these deteriorations happen over-time, knowledge about these repercussions will keep you attentive to your vehicles at all times.

Underneath are some significant consequences caused due to constant over-filling of the transmission system.

1. Heat-Elevation In The Transmission System

Transmission systems are usually hot. When transmission oil is poured into the system, it by nature tends to expand. Therefore, it’s important to leave a certain space for the oil to expand and not over-flood the system. If the system gets swamped, it leads to leakage of the oil further endangering gearbox to overheat.

Instead of providing sufficient lubrication in the system, overloading the oil breaks the frame, ultimately creating high-level frictions between the metal plates, causing severe damage to the gearbox.

2. Aeration In The Transmission System

Excessive fluid can create unwanted pressure in the transmission chambers; it causes fluid leakage all across the transmission frames, further causing a chemical reaction. This reaction aerates the fluid affecting the oil’s functioning quality.

The formation of air-bubbles between the metal and oil ceases the performance of the metal parts. This leads to accelerated metal grinding; if the metal grinding is faster than the usual, it can cause premature degeneration of the gearbox.

3. Breakdown Of The Transmission System

Over-heating, leakages, aeration of the fluid can slowly breakdown the transmission system. Not only does it affects the transmission chambers, but it causes failure of the gearbox as well. These consequences aren’t immediate, but if not attended in time, can cause the terminal failure of the complete transmission system.

However, it is possible to replace the transmission system, which can potentially burn a hole in your pocket. These replacements are highly expensive, and renewal of the complete system can often decline the overall health of the car.


Correct Assessment Of The Transmission Oil In The Car

An ideal amount of oil is crucial for the durability of the transmission system; ignoring it can affect the viability of the car eventually. Every manufacturer recommends the required amount of fluid in the car; these can be enquired at the time of purchase or can be looked up on the internet.

Ideal Amounts for Different Vehicles

Mostly, passenger vehicles take 12 to 16 quarts of fluid, but these measurements are vague. Every car model has a different specification of the required amount of fluid, and the owner should always take that into account. Some cars come with dipstick which makes it easier to check the oil level, for a car model that don’t have dipsticks, owners will have to lift the car to a level and check the fluid from under the car.

Common Mistake When Adding Transmission Oil

Another common mistake that car owners tend to do is refilling the oil every time there is a leakage; this may swamp the transmission system. In such cases, it’s always advised to get it checked by a professional instead of trying methods that can cause further damage to the car.

Also, be patient with the process, it takes a while for the oil to flow in the extreme bottom of the transmission system, in a hurry, chances are you might end up overloading the system


Bottom Line

Nothing in excess is good, this applies to your vehicles as well, for the longevity of your car and to avoid a frequent visit to a mechanic these minor problems need to be addressed immediately.

Though gearbox and transmission, the chamber might look like very inconsequential components in a car you may end up spending thousands of dollars in getting them replaced.