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Dirty Transmission Fluid

How Often Should I Change Transmission Fluid

What causes dirty transmission fluid and how does that bad fluid affect your vehicle? What are the next steps that you should take to resolve the issues? These are mainly the things we are going to discuss in this article. The transmission fluid in your vehicle is an important part of the transmission's health because it provides the hydraulic strength and lubrication needed for the complicated parts to function properly. This fluid becomes dirty or degrades due to heat over time. 

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Also the components of your transmission wear out and “shed” metal into the transmission fluid over time. This changes the fluid's color from clear bright red to gray, brown, or even black. If your transmission fluid is a deep red or brown color, it is possible that it is old and causing more harm inside your transmission. If it's dark brown, it's a sign of burnt transmission fluid caused by overheating. You should also inspect your transmission fluid for any debris. A faulty transmission filter can also cause your transmission fluid to become dirty prematurely.

Dirty Transmission Fluid: Signs of a Faulty Transmission Filter


Contaminants are kept out of the transmission fluid by the transmission filter. There are a variety of issues that may occur with the filter, reducing its ability to do its job effectively. Knowing what signs to look for can help you determine when a repair is needed. Here are some common signs to watch out for:


Smoke or a Burning Smell


A burning odor can occur when the filter becomes clogged with particles that it was built to keep out. It can lead to the terrifying sight of smoke erupting from the engine in extreme cases.


Strange Sounds


If you hear a rattling that you can't put your finger on, it's worth testing the transmission. If a flaw has formed, it must be replaced or the fasteners must be tightened. Filters that become clogged with debris may also be the source of noise.




The transmission filter's job is to prevent contaminating particles from getting into the transmission fluid. If the filter fails to do its job properly, the transmission fluid may easily become too dirty to perform its function effectively. It will burn when pollution exceeds a certain amount. It will require a transmission repair as a result. Check the transmission fluid on a regular basis, not just to see if it's at the right level, but also to see if it's clean.




After the car has been driven from where it has been parked, you will see signs of leaks. It is possible that leakage will occur if the transmission filter is not correctly installed or if the transmission itself has a defect. As part of the transmission, there are a variety of seals and gaskets that can develop cracks and cause a leak. Similarly, a leak may occur if they become dislodged or misaligned. 


Inability to Change Gears


An issue with the transmission filter might have formed if you can't shift gears easily or if it doesn't work at all. Similarly, if the gears grind for no apparent reason or the vehicle surges while shifting gears, the issue may be caused by a defective transmission filter.


Replacement of the transmission filter


The transmission filter should be changed every 30,000 miles or two years, whichever comes first, according to most car manufacturers. When you replace the transmission filter, you can also replace the transmission fluid and the transmission pan gasket. These products are simple to replace and can be done in under an hour.


What Happens When You Have Dirty Transmission Fluid 

  • Vehicle suddenly surges


When transmission fluid has become clogged with a large amount of dirt and debris the drivers could experience an unexplainable surging while driving. It may be because a dirty transmission is impeding proper fluid flow. This can cause the vehicle to leap or surge back and forth without warning. This occurrence is caused by an inconsistency in the flow of transmission fluid.

  • You can hear grinding or other strange noises


When a transmission becomes clogged with dirt, grease, and other debris, it can exhibit symptoms similar to low transmission fluid levels. If drivers hear their transmission grinding or making strange noises when driving, they should check the transmission fluid levels while the vehicle is still running. If the fluid level appears to be normal, then you might have a problem with your transmission fluid being dirty.

  • It becomes difficult to shift gears.


When changing gears, a transmission with too much dirt or sludge in the fluid can cause a sluggish response. Clean transmission fluid is needed for smooth operation and optimum output in all vehicles, whether manual or automatic. If your automatic transmission switches gears too soon or too late then it could be that dirty transmission fluid. Manual transmissions with dirty transmission will be difficult to control if it moves at all.

  • Your gears are slipping.


Excess dirt and pollutants in the transmission can result in a loss of hydraulic strength, preventing the transmission from staying in the proper gear. A dirty transmission can easily obstruct transmission fluid flow, resulting in a lack of pressure required to keep the transmission in gear. If you have no other issues with your transmission besides slipping gears then it might be the dirty transmission fluid.

  • Delayed vehicle movement


Another warning that your transmission fluid is dirty is when your car stalls for one or two seconds after being placed in gear. A transmission flush can be beneficial if there are no other issues with the transmission.

Dirty Transmission Fluid Solution: The Benefits of Transmission Maintenance


  1. Enhances gear operation – When the transmission overheats, the transmission fluid coagulates into a dense, gooey sludge that clogs gears and makes moving between speeds difficult.


  1. Enhances Fuel Efficiency– When the transmission is working properly, it puts less pressure on the vehicle's other mechanical components. By reducing the amount of friction generated by moving and spinning parts, energy is increased and transferred to the wheels, improving fuel economy.


  1. Prevents Overheating – Particles from the transmission and metal shavings collect in the transmission fluid over time. As it travels, the transmission and fluid begin to heat up greatly, causing particles to burn and internal components to overheat, resulting in device failures.


Should I Get a Transmission Flush or Fluid Change for Dirty Transmission Fluid?


The transmission in your car is crucial because it sends enough power to the wheels to enable you to drive at certain speeds. Most drivers are aware that transmission issues are associated with costly repairs. Using your parking brake, coming to a complete stop before shifting gears from reverse to drive, and, most importantly, performing simple maintenance will help you prevent transmission repairs.


Transmission fluid is used to cool and lubricate your transmission, just as oil is used to lubricate your engine. Transmission fluid changes and flushes are part of transmission repair. When it comes to those options which one is the right one for you?


Transmission Fluid Change Versus Flush


Transmission Fluid Change


When a technician changes the dirty transmission fluid, the transmission pan is removed and drained, and the filter, if applicable, is replaced. The transmission is then refilled by the technician. However, not all fluid can be separated, with up to half remaining in the torque converter and cooler lines. Even if not all of the fluid is fresh, most of the old, dirty fluid is replaced, making it more powerful than before.


Failure to replace transmission fluid, and in some cases, transmission fluid that is heavily contaminated, can endanger your transmission by causing overheating and making it work harder than required. Ineffective transmission fluid shortens the life of your transmission and can cause it to fail. Every 30,000 miles or every two years, whichever comes first, you must change your transmission fluid.


Transmission Flush


The benefits of a flush are self-evident. All of the old, contaminated fluid is drained and replaced with fresh, high-quality fluid. As a result, your transmission should run cooler and be better protected against clutch, gear, and bearing wear.


Since the new fluid has more efficient frictional properties, you'll find smoother, more consistent moving. Flushing the transmission will also help to disinfect it. Due to the intense heat that breaks down the fluid, sludge and other pollutants will collect in it. After that, the pollutants flow through the transmission before settling in the filter.


However, until the pollutants can be safely captured by the filter, they risk being lodged in the valve body's narrow passages, resulting in poor shift efficiency. Flushing also helps you to use a flush additive to help clean the transmission and eliminate accumulated sludge and other pollutants more effectively.


Transmission flushes should be performed every 45,000 miles or three years in lieu of a drain and fill or to replace fluid changes entirely. Many people claim that a transmission flush is more efficient than a drain and refill because the old fluid stays in the transmission after the shift, contaminating the new fluid and lowering output.


A flush removes the old fluid with a flush machine and replaces it with new fluid, allowing the transmission to work at its best. But it is much more expensive than a quick drain and refill. In any case, opting for a fluid flush or a drain and refill is preferable to not doing any transmission maintenance at all. 


But some people still advise against flushing a transmission with rusty, dirty transmission fluid. Due to eddy currents, the flushing procedure can cause some fluid to flow in the opposite direction of normal flow, increasing the risk of debris being dislodged and settling somewhere it shouldn't. Also since some vehicles have a sealed transmission, a fluid flush or shift isn't necessary. To be sure you’re doing the right thing, best consult your owner's manual.


It's important to keep in mind that a transmission flush isn't the same as a fix. Transmission flushes can help avoid significant transmission problems in the future, but they can't guarantee it. Many transmissions fail after a transmission flush, not because of the flush, but because the transmission was on the verge of failing to begin with. A transmission flush isn't meant to fix issues with the transmission; rather, it's meant to keep it in good working order


Dirty Transmission Fluid: Other Frequently Asked Questions


What does Black Transmission Fluid mean?


Transmission fluid that is nearly black or black in color indicates that it is old, filthy, polluted, and has oxidized if accompanied by a burnt toast odor. Your transmission is now alerting you that something is wrong. Repair or replacement of your transmission may be necessary if it shows signs of slipping or hesitation.


Should I change my transmission fluid if it's brown?


The fluid is fresh if it is vivid pink. There's no need to change it. It has to be replaced if it's light brown with a touch of pink. It will be really dark brown if it hasn't been replaced in a long time.


What does it mean if your transmission fluid smells burnt?


This burning odor may be caused by overheated or low transmission fluid. Fresh transmission fluid has a sweet or sour aroma. When the smell changes to burnt, the transmission fluid has degraded and the machine is overheating, increasing friction and corrosive activity in the engine.


Should I change my transmission fluid if it is black?

If your car's transmission fluid is dark, it's a dead giveaway that your transmission fluid is much older than it should be. As transmission fluid ages, it will change color from red to light brown to dark brown to black. It will immediately alert you to the need for transmission fluid replacement.


Is it bad to change transmission fluid on high mileage?


It's dangerous to change the transmission fluid in a vehicle with a lot of miles on it. It's not a good idea to do it unless the transmission is in good working order and the fluid is top-notch, as it could lead to transmission failure.


Transmissions play an important role in your vehicle's operation. You won't get too far without a working transmission. Be sure to get rid of dirty transmission fluid by getting maintenance performed on your transmission on a regular basis to keep it running at its best.


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