Can Dirty Transmission Fluid Cause Shifting Problems?

Dirty transmission fluid is a major cause of shifting problems. When the fluid gets dirty, it reduces its effectiveness.

Now your transmission system will not be able to receive enough hydraulic power and lubrication, which could cause a failure in the transmission system. 

This article will cover the impact of dirty transmission fluid on your transmission system.

We will discuss the symptoms and solutions and answer important questions about transmission maintenance for your vehicle.

Can Dirty Transmission Fluid Cause Shifting Problems?

A dirty transmission fluid can cause a transmission shift problem in your vehicle. In addition, Transmission fluid dirty or contamination can clog the gear and prevent it from shifting efficiently. The fluid color can help you know the condition of the fluid in the car. A darkish or brownish color is a sign of old or contaminated fluid.

We recommend paying close attention to your vehicle’s transmission fluid level and quality. Once your oil is contaminated with coolant or too old, all additives and other components that keep the fluid active become neutralized.

The fluid will no longer be able to carry out both lubrication and hydraulic functions, which does not allow a proper shift in gear when needed.

Also, when observing your fluid, check for metal particles in it. If you can find metal particles in the fluid, it could mean you have a transmission problem.

At this point, you may have to get a proper diagnosis and repair and change its fluid. 

Finally, a clear transmission fluidallows for a smoother and more efficient gear shift.

5 Symptoms of Dirty Transmission Fluid

There are signs of dirty transmission fluid, which shows it is time to change the fluid.

The symptoms could be attributed to signs of a bad gearbox. However, you should check your transmission fluid when you notice more than one of these symptoms.

Below are the symptoms of dirty transmission fluid.

1. Unusual smell

Transmission fluid has a sweet, sugary smell; anything otherwise is a sign of a dirty or contaminated transmission fluid. It is why you need to check your fluid regularly; you can tell if the oil needs to be changed to remove transmission fluid smell.  

2. Shift Issue

One major sign of a dirty transmission fluid is a problem with gear shifting. As we have mentioned earlier, a bad fluid shows that it is less effective. The fluid cannot perform lubricative and hydraulic functions making it difficult and sometimes impossible to shift gears.

Also, the shift issue could arise due to the clogged filter from the prolonged use of dirty fluid. Once the filter is clogged, the fluid will be unable to flow, causing seizure in transmission.

3. Disturbing noise

Another symptom of dirty transmission fluid is strange grinding, clunking, or other sounds. These sounds would be significant whenever you try to change the gear. It could be a result of internal damage caused by the dirty fluid. 

4. Engine running hot

Many people do not know this, but a dirty transmission fluid could cause your engine to run hot. When you run your vehicle on dirty fluid, it clogs the filter and reduces or stops the fluid flow.

Once the fluid does not flow, it will not move through the cooling tank and cool. It creates a large amount of heat. In addition, increased friction in transmission adds to the heat, which is then transferred to the engine. 

5. Slipping gear

A gear slip happens when the gear cannot stay in one gear and keeps shifting. It happens when there is insufficient hydraulic power to keep the gear in one position without shifting. It happens when the transmission fluid is old or contaminated.

Will Changing Transmission Fluid Help Shifting?

Changing transmission fluid will help shift if the problem with your gear is not mechanical.

The fluid is a major source of hydraulic power supplied to the transmission system.

With every gear change, the hydraulic fluid helps transmit power which initiates the gear change.

When you have a low or dirty transmission fluid, the fluid has little or no hydraulic power to initiate the gear change.

Using a cleaner fluid helps generate hydraulic power in the transmission. Hence a better and smoother change in gear in your vehicle.

Furthermore, when you notice a black transmission fluid ora significant change in color from its original, you should change the fluid urgently.

How Can I Make My Transmission Shift Better?

A good maintenance culture will help reduce the risk of having problems with your transmission system.

Below are some tips to help your transmission shift well and reduce the risk of a system failure.

1. Change your transmission fluid

If you want a proper and smoother transmission shift regardless of your transmission type, change its fluid at the recommended interval.

You should change the transmission fluid between 30,000 to 60,000 miles if you have a manual transmission system. For automatic transmission, change the fluid between 60,000 to 100,000 miles.

2. Lower gears when driving with heavy loads

Make use of the most suitable drive selection in every driving condition. When driving in traffic or towing heavy loads, try to use drive selections for the transmission. Avoid overdriving when bearing heavy loads, as it could put too much pressure on the gears.

3. Change driving habits

Avoid bad driving habits that could damage your gear. For instance, shifting from drive to park when the vehicle is still moving.

Also, you could study your vehicle and see when the transmission shifts when driving. Knowing what RPM your automatic transmission will shift can improve driving habits and help you quickly determine when something is wrong with the system.

4. Have proper tire alignment

The tire alignment contributes to the driving condition and the operation of your transmission system. Check for alignment issues and, if found, fix them immediately to improve transmission.

5. Use the right tire size

Using the wrong tire size will affect the tire alignment of your vehicle. It most especially happens when the tires’ sizes are different. Once the alignment is affected, the transmission may also be affected.

6. Have proper engine maintenance

The temperature condition of the engine plays a major role in how the transmission will work. If your engine’s cooling system is down and the engine overheats, it could transfer to the transmission system and cause it to overheat.

Try to have the engine checked or serviced appropriately and kept transmission cool to avoid engine and transmission failure.


Dirty transmission fluid is caused by prolonged use of transmission fluids. It harms your transmission system and should be avoided with a regular fluid change.

Also, we recommend changing the filter along with the fluid to keep the fluid clean and free-flowing.

Akindayini Temiloluwa

I am Akindayini Temiloluwa, an automotive expert writer and car enthusiast. I have over three years of experience in the automotive writing niche and have completed over 300 pieces of content from 50 projects. I have vast knowledge and skill in vehicle repairing, all mechanical work, car upgrades and maintenance. My goal as an automotive content writer is to simplify the most challenging concepts for my readers, help them self-diagnose what may be wrong with their vehicles and offer real value for their time.

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