Top 6 Symptoms of Bad Transmission Fluid

Symptoms Bad Transmission Fluid

After constant usage, there are chances that the quality of the transmission fluid will reduce, causing it to go bad. But how can you tell your transmission fluid has gone bad and needs changing?

Some of the most common symptoms of bad transmission fluid include:

  • Unusual noise
  • Gear slips
  • Bad fluid quality
  • Engine overheating
  • Burning smell
  • Stiff gear shifts

We’ll discuss everything you need to know about transmission fluid and when to change i.t

Symptoms of Bad Transmission Fluid

1. Bad Fluid Quality

The easiest way to tell if you have a bad transmission fluid is to check the quality.

Your transmission fluid is bad if it has a dark burnt color. The standard color of good transmission fluid is transparent red. Anything different from this is bad.

You can confirm the quality of your transmission fluid with a clean white paper towel and a dipstick. Pull the dipstick from the transmission and smear the fluid on the clean paper towel.

If the fluid has some dark coloration or brown color, there are chances that it is either old, burnt, or dirty.

2. Burning Smell

Transmission fluids are meant to lubricate the moving parts of your car and reduce friction. Bad transmission fluid has lost its ability to lubricate properly. This will result in a burning smell from the frictional effect of the moving parts.

In extreme cases where the issue is left unattended, these parts might overheat or burn, complicating the existing issue.

Sometimes, the burning smell might mean that the transmission fluid has expired or its quality has reduced over time. It can also mean that it is overheated or has broken down.

A good transmission fluid smells sweet or what we might term “odorless.” Your transmission fluid is bad if it has started smelling like burnt toast.

3. Stiff Gear Shifts

One of the symptoms of a bad transmission is stiff gear shifts or difficulty with shifting your gears.

The transmission fluid lubricates the gears and allows smooth operations of the gear system. When the transmission fluid is bad, you should notice some difficulty trying to change gears.

The problem might extend to the inability to use the gears at all. This problem will worsen when your car refuses to switch to reverse or starts shifting gears on its own.

Sometimes, transmission fluid goes bad because of dirt contamination. When it becomes dirty/bad, free flow is restricted. This makes it difficult for the transmission to build enough pressure and hydraulic power to shift gears.

You might notice a sluggish gear response or an inability to respond. The bad transmission fluid can go as far as clogging the transmission filter, preventing enough lubrication on the gears. This can lead to wear and tear on the bands and clutches that should enforce gear change.

4. Unusual Noise

Grinding noise is one of the symptoms of bad transmission fluid. When the transmission is bad, it starts failing in its primary duty: to lubricate the moving parts of your car. Friction builds up, causing these parts to grind when they want to function.

The grinding noise can also happen if the bad transmission fluid has clogged the filters. Cases of grinding noise from bad transmission fluid are most noticeable when you want to shift gears. The grinding noise will increase as much pressure is mounted on these parts.

5. Gear Slipping

Bad transmission fluid can cause slipping of gears. When the transmission fluid is bad, the pressure to properly engage the gears is not achieved.

If the transmission is not getting enough pressure, the gears will always slip anytime you try to engage them.

6. Transmission Overheating

The transmission fluid helps keep the temperature of the transmission in check. When it becomes bad, the cooler lines are clogged. This will result in a surge in the transmission temperature, leading to overheating.

The overheating might get too high that your car might trigger a “check engine light.” The level of transmission overheating caused by bad transmission fluid will vary based on how long you ignore it.

At around 220°F, you will notice varnish formation on the metal parts of your transmission system.

At 240°F, you should notice the hardening of rubber seals. These seals might start leaking, giving room for a replacement.

At 260°F, there are high chances of transmission slippage. If you allow the transmission system to hit up to 295°F, then you should get ready for the transmission system to fail.

What Happens if You Never Change Transmission Fluid?

You are putting your transmission system at risk of damage if you never change your transmission fluid.

Leaving the transmission fluid for a long time without changing it will cause it to become dirty, go bad, and consequently break down.

This will impact the lubrication effect of the transmission fluid and the amount of hydraulic pressure that should be generated.

There are chances that this will increase the amount of friction in the moving parts of your engine, causing them to wear and tear. You wouldn’t want to witness the case of overheating due to not changing the transmission fluid.

On an average scale, it is recommended that you change your transmission fluid after every 60,000 – 100,000 miles for automatic transmissions. For manual transmissions, you should change after 30,000 – 60,000 miles. This might vary depending on how frequently you use the car.

There is nothing wrong with changing the fluid earlier. You must change, drain or flush whenever you notice that you have a bad transmission fluid.

Does the Check Engine Light Come on for Transmission Fluid?

Yes, transmission fluid can cause the “check engine” light to come on. There are many instances that the transmission fluid can trigger a check engine light. It might be a case of no lubrication or low transmission fluid.

When the transmission fluid is low, bad, or dirty and cannot lubricate the transmission system or moving parts properly, the engine can start overheating, causing the check engine light to come on.

You might need to check the fluid level or the state of the fluid to know if you need to top it or change it.

What To Do When Your Transmission Fluid Goes Bad

There are a lot of arguments on the best thing to do when your transmission fluid is bad. The solution for a bad transmission fluid depends on a few factors supporting the damaged fluid.

However, here are quick ways to fix a bad transmission fluid:

1. Replace the fluid

Many drivers will disagree with the idea of replacing the bad transmission fluid. The arguments lie in the efficacy of draining or flushing an old transmission fluid.

Whichever motion that is thrown, we believe in the importance of replacing transmission fluid, more importantly, how you replace the fluid.

Instead of draining out all the old fluid in the transmission system, we advise that you drain more than half of the bad fluid, leaving some little left that you can top up with good fluid. This keeps you on the safer end.

2. Top the fluid level

You can fix a bad transmission fluid by topping it with new oil. This is effective if the transmission fluid is still good enough but has gone way below the required fluid level.


We’ve guided you through all major symptoms of bad transmission fluid, and we believe you know when and how to inspect your transmission fluid.

You might consider seeking the services of an expert to help you check your car if the symptoms persist.

Frequently Asked Questions

Will new transmission fluid help shifting?

Yes, new transmission fluid can help to shift. You need to know that changing your transmission fluid cannot solve the mechanical problems of your car. If the shifting problem was caused by low or bad transmission fluid, getting a new transmission will solve the problem.

Will changing the transmission fluid and filter help with slipping?

Yes. Changing transmission fluid and the filter will help fix a slipping problem. This will only be effective if the slipping problem is caused by a low, bad, or burnt transmission fluid.

What happens if you drive with low transmission fluid?

Consistently driving on low transmission fluid will damage your transmission system. The damage will start from minor slips and difficulty in operation before it extends to overheating and permanent breakdown. You must top or replace your transmission fluid when you notice that it is getting low.