What Does Transmission Fluid Smell Like? (Gas, Fish, Burnt)

When it comes to transmission fluid, you can find it only in two formats. One is the original where oil hydrocarbons are manipulated and the other is synthetic. The latter is made through chemical reactions. Plus, it lasts longer and is of higher quality than the original.

Transmission fluid is supposed to be either odorless or comes with a slightly sweet fragrance. Any other odor is telling you that you may have a problem with your transmission or its related components. Even though it is made from oil, it does not have that oily smell.

To learn more about this topic, just continue to read our article. It has the information you want to know about so you will be able to recognize when there is a problem in your transmission. Keep reading to get this important information.

Is Transmission Fluid Supposed To Smell?

Not really. It is supposed to have no odor when it is in fine condition. If you do not smell anything then you do not have to take any preventive measures. However, there is one slight adjustment that needs to be made to that statement.

Sometimes, transmission fluid will smell a bit sweet. This odor is also telling you that the fluid is okay and you need to do nothing when you detect its odor. Just keep in mind that different people will have different opinions on these two odors.

Many people will focus on the burnt smell that this fluid contracts as it wears out over time. Also, if you smell a sweet odor when you are near your car, the fluid may be okay but if you are noticing it, there may be a leak somewhere.

The only time you should smell the fluid is when you open the dipstick and pour some fluid inside. At any other time, you should not smell the transmission fluid unless something is wrong.

What Does Transmission Fluid Smell Like?

There are several different odors related to transmission fluid. The first two you already know about, have no odor or a sweet odor. When you do not detect an odor, then your transmission fluid should be fine and there are no leaks.

If you detect a sweet odor, then you are still fine unless that odor is coming from outside of your transmission. Then you need to find a leak. Then, if you detect a slight burnt odor, the transmission fluid is breaking down and may not cool the transmission as well as it should.

Your course of action will be to replace the fluid. If you smell a distinct burnt odor, then there may be some damage to the fluid and possibly to your transmission. But the fix is to flush the system and change the fluid.

Next, if the odor you detect is a severely burnt smell, then the fluid needs to be changed asap. Check your transmission for any damage. There is one category we are not sure what is meant by its label.

It is called the vanished odor and there is no explanation for that label. But if you come across it, the fluid needs to be changed as it is damaged and not good for the transmission

Does Transmission Fluid Smell Like Gas?

No, it does not. While both are made from the same original source, transmission fluid, depending on the manufacturer, does not have any odor to it. If it smells like gas then it is an indication of a gas leak somewhere in your fuel system.

Gas is being injected into your transmission and that may cause some parts to degrade or get damaged. If you are not a transmission mechanic, then find an honest one to have him look at your transmission.

The leak will need to be plugged in as soon as possible to avoid making any slight damage more severe. Gas will be a contaminant that will ruin the transmission fluid, keeping it from doing its lubrication job.

One way to monitor your fluid’s odor is by taking the dipstick out and giving the fluid on it a good whiff.

Transmission Fluid Smells Sweet


According to our sources, this is a normal odor that tells you that nothing is wrong with your transmission or the fluid itself. It is a toss-up if you will get an odorless or a sweet-smelling transmission fluid brand or not.

The odor is up to the manufacturer and they may decide to add a fragrance to help you distinguish it from other fluids. Or the odor will give you a better marker to tell if there is something wrong with the fluid.

The times you have to worry are when the fluid smells like it has been burnt. Or if the sweet odor has disappeared. In either case, you should have your mechanic change the fluid as quickly as possible so you do not harm your transmission.

As long as that sweet odor remains, then you know that there is nothing wrong with your transmission and you can drive safely. Just keep a nose out for any change in the odor so you know there is a problem before it is too late.

Transmission Fluid Smells Like Fish

The legend has it that many moons ago, the original ATF was made from sperm whale oil. That component gave the automatic transmission fluid that fishy smell. That means that in those days, the days of your grandfather or great-grandfather, a fishy smell meant the fluid was good.

That is the legend. Contrary to that factoid, the fishy smell usually only comes when the ATF is really old. But that may not apply to all transmission fluids. Some brands seem to have that fishy smell even when the fluid is new.

Castrol TransMax Import and Mobil 3309 were two brands that were mentioned that came with that fish smell. As we said earlier, the odor you get is up to the manufacturer so this may be a normal odor for some brands.

If the fluid is new and has never been opened, then just hold your nose till you are done. Or take a deep breath before pouring into your transmission. Once you put the dipstick back in the odor should go away.

Transmission Fluid Smells Like Cat Pee

The only explanation we could find was that the transmission fluid may be breaking down and it needs to be replaced. Part of the problem is those two little words at the end of the sub-heading- cat pee.

You would be amazed at all the non-cat related items that smell like cat pee. It is possible that your transmission fluid has one of the following chemical ingredients in it that tends to smell like cat pee:

- Ammonia

- Methanethiol

- 1-Dimethylhydrazine

- Ammonium hydroxide

- Freon

If there is a leak somewhere and freon, etc., has leaked into your transmission. You may have a gas leak as some gas does smell like cat pee. Or, you just have a mold problem somewhere in your vehicle.

Tracking the source of this odor is not very easy as even transmission websites may mention this odor but they do not explain its source. Except to say there is something wrong with your transmission fluid.

The go-to fix for any odor problem is to change the fluid. That would most likely be the solution to this problem.

What Does Burning Transmission Fluid Smell Like?


While different items have distinct burnt odors, for example, you can tell burning plastic from its distinct odor, burning paper from its distinct woodsy odor, and so on. Transmission fluid is merely described as a slight, distinct, or severe burnt odor.

The burnt odor is due to the transmission or the fluid overheating. This is not a good smell. It is telling you that the fluid is breaking down and you are going to have a serious transmission problem if you do not take action right away.

To avoid an expensive transmission repair you need to pay attention to those different odors. The slightly burnt odor is the early warning signal and as soon as you smell it you should change the fluid.

Then you should see what is causing the overheating in your transmission. Of course, smells won’t be the only symptom telling you you have a problem with your transmission.

Not being able to shift smoothly is another one, smoke coming from the engine compartment is another, as is spotting transmission fluid on the ground under your transmission.

Transmission Fluid Smells Like Burnt Rubber

The best explanation is that something is burning in your transmission. Like cat pee, there is no specific explanation even from transmission websites. They just say that if there is a burning smell, doesn’t matter the odor, then something is wrong with your transmission.

Aside from the signs we mentioned earlier, you may have a grinding noise telling you that something is wrong, or the service engine soon light is always on. All of these signs will confirm what your nose is telling you.

If it smells like something is burning, go to a mechanic as quickly as possible and let them find the source of the problem. They will have the expertise, experience as well as the tools to solve the problem for you.

Do not ignore the odor unless it smells sweet. If you do you are only compounding the problem and making it a lot worse. When you do that, you can start seeing that repair bill climb higher and higher.

Why Does Transmission Fluid Smell So Bad?

Part of the reason for this is because of the contaminants that eventually enter your transmission. These contaminants will have their own odor and when they get old, they will only smell worse.

But that is only part of the problem. Another part would be that the transmission fluid manufacturer has added a fragrance or component to their product that does not smell that good.

It seems that Castrol and Mobile have done this as some owners have reported a bad fishy odor even when the fluid is new. Then, when the transmission fluid gets sold, it starts to stink.

Even if left unopened, it seems that the fluid develops an odor over time. It will just tell you that you should not use it in your transmission as its shelf life is near the end and the components may be breaking down due to age.

Finally, the fluid will smell bad because the transmission or the fluid overheated and burnt anything never smells good. Your nose will be a good source of news letting you know you have transmission issues.

Smelling Transmission Fluid After a Change


Go ahead and try. If you have put new transmission fluid inside your transmission, then chances are you may not smell anything. Many fluid makers do not put an odor in their fluid.

However some do, as evidenced by Castor and Mobile, and the odor can be sweet or it can have a fishy smell. The latter is not very attractive at all. But its presence does not indicate something is wrong with the fluid.

Most of the time, your transmission fluid should not smell or it should have a sweet odor to it. That is when you know the fluid is good and can protect your transmission.

If you smell something after the change, then the problem may be with the transmission and you need to have it looked at to find out what is wrong. The transmission can overheat and ruin the fluid.

The best way to tell that there is something wrong with your transmission fluid is by its color. There are several different colors that will tell you if your fluid is bad or not. Here you can find our transmission fluid color chart.

Smell Transmission Fluid But No Leak

This is an interesting situation as it is hard for the fluid to escape the transmission at any time. That is without any leak helping it to escape. If you smell transmission fluid but do not see a major leak anywhere, rest assured there is a leak.

It may be small and it may not produce large drops of fluid but it is finding a spot where it can get out of the transmission. It could be that the fluid only finds the leak when the car is running.

That means you would have to leave the car on while you look at the transmission. This small leak can be in the gaskets, the fluid pan nut, or other transmission parts.

However, transmission fluid does not evaporate so that is not going to be the source of your low fluid levels. Look long and hard for a leak.

Transmission Fluid Smell Inside The Car

Generally, the only time you will face this situation is when there is a leak somewhere in the transmission. The reason you can smell it inside your car is that the odor has found its way through your open vents.

To stop this odor and possible serious transmission problems, you need to have your mechanic look for and fix the leaking part. It could be the gasket or the hydraulic line is loose, cracked, or has a hole in it.

While you are driving and you smell the fluid, close the vents to avoid any possible nose irritation. Then get to a mechanic as soon as possible as a leak only means trouble.

How To Get Rid Of Transmission Fluid Smell


For the most part, the go-to solution would be to replace the transmission fluid. That has been the solution for every odor that can possibly be a part of the fluid. That is the easy repair.

The more difficult repairs will be finding the leaks that let the odor and the fluid escape. If they are large, then those leaks will be easy to spot. But if they are small, it may take some time to find the leak and fix it.

If the smell lingers, you can clean your car’s interior with baking soda, use an air freshener or simply close the vents. That is a side issue though. If you smell burnt fluid and only change the transmission fluid chances are you may smell that burnt odor in the near future.

If you do not change your driving habits, how much you tow or do not cool your transmission that well, then you should encounter that odor once again.

Some Final Words

Your nose will tell you when you have a transmission problem. The different odors that come with this fluid will let you know if everything is okay or if you have a problem.

The transmission could be overheating, you have a failed part somewhere, or even a small leak. No matter the problem use your nose to detect the problem and avoid having a huge transmission repair bill.

No odor or a sweet odor tells you that nothing is wrong and you can drive all day long without a problem.

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