What happens if you put transmission fluid in the oil?

Why would you want to use or mix transmission fluid in the oil in the first place? Surely, there are some benefits, or you think so. The fact is, transmission fluid serves a totally different purpose in the engine. That is why its name is not ‘engine oil.’ Let’s check What happens if you put transmission fluid in the oil?

 And for the same reason, you are not supposed to find transmission fluid anywhere else but in the transmission parts.

But what if you find transmission fluid in other areas of an engine? Or, what if you mix the transmission fluid with the engine oil? What will happen in these cases? Let’s find out.

What happen if you put a small amount of transmission fluid in oil?

Nothing much will happen if you put a small amount of transmission fluid in the oil. Because the transmission fluid’s base oil is the same as the engine oil. For this reason, it won’t cause much trouble. But you have to ensure one little detail to avoid dangers.

If you want to put a small amount of transmission fluid, don’t mix the types of engine oil. Make sure the transmission fluid is of the same type of engine oil you are using in your vehicle.

Another thing is that people used to believe transmission fluid was a great cleaning agent. In the instances of an oil change, they tend to use transmission fluid to keep everything clean.

Although transmission fluid is not a great detergent, it proved to be right about the myth in the past. The engine oil in the past was not that good.

In addition, people experienced a lot of sludge buildup while changing the oil. Putting a small amount of transmission fluid in the engine oil was enough to solve these issues.

But things are not the same these days. The engine oil is a lot better than in the past. The oil itself is a better cleaning agent than the transmission fluid. That is why putting even a small amount of transmission fluid is not worth it.

What if you have done it by accident? As per our study, it is not a thing to worry about, as long as you are using a transmission fluid recommended by the manufacturer. Should I Change Transmission Fluid After 100k Miles?

ATF in engine oil and adding ATF to engine oil

ATF stands for “automatic transmission fluid.” It is a type of fluid that suits vehicles with automatic transmission. That means if you have a vehicle with an automatic transmission, chances are you are using automatic transmission fluid in some of the engine parts by default.

Now that you are clear about how ATF works, let’s discuss two popular instances.

What if you find transmission fluid mixed with engine oil? Is it bad?

The engine parts where the transmission fluid is used normally remain sealed. So, things are not normal if you find transmission fluid in engine oil. What do you do in this case? Is it dangerous for your engine and vehicle?

No. The chances of falling into unwanted dangers because of this issue are very rare. The reason behind the answer is that the transmission fluid is also of the same base oil that your engine is using.

You should not be worried if this happens. But taking your vehicle to the mechanics for further inspections is always a better choice.

But what if you add ATF intentionally to the engine oil? Is it dangerous?

The answer is still negative. The reason is the same that we stated in the first answer. But you should not do this unless your vehicle model is very old.

Because most modern vehicle models use modern engine oils that are far better than the transmission fluids. Even the cleaning agents are better in the modern engine oil.

So, although there won’t be any major harm done, we do not recommend adding ATF to engine oil.

ATF engine cleaning trick

There was a time when people used to mix transmission fluid with engine oil. People did that so that the ATF could clean the engine oil. Well, back in the days, it worked. People actually thought of this activity as a trick to clean the engine or engine oil. Check Mercon V vs Mercon LV Proper Guide on Transmission Fluid ATF

The process was simply putting transmission fluid in the engine at a small amount and running the engine for a while.

Nowadays, this trick is nothing but a myth. The engine oil these days is so much improved. As there are fewer cleaning agents in ATF than the engine oil itself, we don’t think this ATF engine cleaning trick will work anymore.

However, this trick may still work if you own an old vehicle that uses an old transmission system and needs dated engine oil. Does Changing Transmission Fluid Help Shifting?

What is 1 quart of transmission fluid in oil

Back in the 1970s, mechanics used to recommend putting 1 quart of transmission fluid in engine oil before changing it. Nowadays, engine oils are cleaner. You won’t need 1 quart of transmission fluid. If you want to go this way to clean the engine oil, you will need much less than that of 1 quart.

What happens when you mix transmission fluid with engine oil?

You may have had a primary idea about how mixing transmission fluid with engine oil goes. Anyway, mixing transmission fluid with engine oil may lead to any of the following events. It doesn’t matter whether you mix ATF intentionally or get engine oil mixed with transmission fluid by accident.

1. It may clean the oil

It is the only case where mixing the transmission fluid with engine oil may come out in handy. If your vehicle is old and needs dated type oil, adding transmission fluid to engine oil will be a good idea.

If your engine has a habit of building up sludge, putting a small amount of transmission fluid will give you better results.

In another case, if you buy a used vehicle, make sure to know about the cleaning process of engine oil. Chances are, you may need to mix transmission fluid.

2. Nothing will happen

Mixing transmission fluid with engine oil to clean or improve the oil is nothing more than a myth in the present days. You may still want to see what really happens if you do so.

 Or, you may accidentally end up mixing transmission fluid with oil.

In the best-case scenario, nothing bad will happen. If you manage to use the recommended transmission fluid, it may not cause any benefits but still won’t harm the oil or engine.

3. The performance will be lower

We have already said this a lot of times in this article. The engine oils are a lot better nowadays.

The additives that are being used with the engine oils are almost perfect for serving their purpose. You won’t need anything more to improve the engine oil.

If you mix ATF with engine oil, in one case, the additives may not add up. Consequently, the engine oil will become less efficient and may not provide the peak performance it was supposed to.

4. ATF may change oil viscosity

In the worst-case scenario, transmission fluid may change oil viscosity drastically. You should already know how important oil viscosity is.

The performance of the engine oil depends a lot on the viscosity. On the other hand, changing the viscosity will alter the oil type.

A common warning we have frequently been giving throughout the article is not to mix oil types while adding transmission fluid to oil. If that happens, you may face serious issues with the engine because changing the oil type will heavily affect the engine.


Can you mix oil and transmission fluid for recycling?

The answer largely depends on the area you are currently living in. You have to consult with your local recycling administration to know the clear answer.

In some states, it is allowed to mix oil and transmission fluid for recycling. And in some states, it is not. If your local administration allows you to mix, you can do so.

 If you don’t know whether it is permitted or not and ask for our recommendation, we won’t recommend it. Because there is always a chance that your state may not allow it.

Can I mix transmission fluid with motor oil?

Similar to mixing transmission fluid with engine oil, mixing transmission fluid with motor oil also depends on your state regulations.

In general, there isn’t much problem mixing motor oil with transmission fluid. Because motor oil, transmission fluid, engine oil, PS fluid are of mostly the same weight and hydrocarbons.

But we always recommend consulting with an expert recycler before mixing any kind of fluid.

Regardless of the oil or transmission fluid type, you must not mix solvents, paint, brake fluid, or antifreeze.

These can contaminate the engine oil very badly and become a hazardous substance. If you accidentally mix them, you have to get rid of the mixture or substance immediately.

Transmission fluid in oil to clean lifters

This is an old trick. You have to replace 1 quart of engine oil with ATF. After that, you have to drive or run the engine for a while. Most experts say you have to run the engine for around 20-30 minutes.

However, this trick may or may not work. But you can rest assured that there won’t be any major problems as long as you stick with the recommended transmission fluid.

Is oil and transmission fluid the same?

No, they are not. Although transmission fluid and engine oil are almost identical in base materials, they are still not the same. Their purpose is different. The primary function of the engine oil is to provide lubricant to the engine mainly. On the other hand, transmission fluid is both lubricant and hydraulic fluid.

You may think of using transmission fluid as engine oil as both are lubricants. You should not because they are made for serving different purposes.

Can you flush an engine with transmission fluid?

We don’t suggest flushing an engine with transmission fluid. Although you ‘can’ flush the engine with transmission fluid, doing so won’t provide many benefits. In the old days, people used transmission fluid instead of dedicated engine flush. And they actually got the job done.

But things are not the same now. The dedicated engine flush is very effective. For this sole reason, you should not waste your money on buying transmission fluid for flushing purposes.


Can transmission fluid mix with engine oil?

Yes, it can. If you do so for cleaning purposes, we don’t recommend doing it. The transmission fluid nowadays has less detergent power than engine oil. That is why spending on transmission fluid for cleaning sludge will be a waste of money.

What happens if you accidentally put transmission fluid in the oil?

In that case, the first thing you have to ensure is whether you have put the recommended transmission fluid. If you have done it with the recommended one, you don’t have to worry much. If you accidentally put transmission oil that is not recommended, you have to immediately take your vehicle to the repair shop.

How do I remove transmission fluid from my engine?

You can remove transmission fluid from the engine in two ways. You can suck out the fluid with the help of a filler tube. And if you can manage a vacuum transmission fluid pump that is hand-operated, your task will be even easier and simpler.

Does transmission fluid float on oil?

No, the transmission fluid won’t float on oil. The reason behind the answer is that both are made of hydrocarbons and have the same base oil levels. People have been using transmission fluids as a small amount in engine oil for a long time. That is why if transmission fluid floats on oil, it means things are not right.

What happens if you never change transmission fluid?

People often change transmission fluid to improve the transmission. If you want to keep the transmission in good condition for a long time, it is highly recommended to change the transmission fluid on a regular basis.

However, if you never change the transmission fluid, the transmission won’t perform at its peak. The lubrication won’t be good, and heat distribution will also be messy.

Will gear oil hurt an engine?

The viscosity grade of gear oil is completely different than engine oil. Gear oil is way thicker than engine oil. That is why if you use gear oil instead of engine oil, it will definitely put pressure on the engine. Because gear oil will require more power from the engine. As a result, it will eventually damage engine parts in the future.

What if I put oil in the transmission?

At worst, you will risk losing the whole transmission. Engine oil or other types of oil may provide poor lubrication or overheating. Consequently, it may lead to engine failure. There is a theory you can follow in cases of oil or fluid replacement. You can always replace ‘oil’ with ‘oil’ and ‘fluid’ with ‘fluid’ without much hassle. But never think of doing vice versa.

Wrap Up

You may get the idea of mixing transmission fluid with engine oil from one of your neighbors or some relatives. But we don’t recommend doing so.

In the worst-case scenario, you may end up damaging some of the engine parts. Why risking the engine parts when mixing the fluid with oil isn’t even worth the money?

Even if you decide to perform this trick on one of your old vehicles, you must consult with an expert before doing so.

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