Transmission Fluid in a Gas Tank: What REALLY Happens?! (Explained)

Transmission fluid is an essential product for every engine, both in manual or automatic transmission. It eases gears’ function and allows them to work smoothly by avoiding direct and rough grind. Now, while it’s helpful to the engine, you may wonder what would happen if you or someone put it on a gas tank by mistake. So, you may ask:

If you put transmission fluid in a gas tank, what really happens? If you put transmission fluid in your gas tank, it can cause contamination to the oxygen sensors. Most transmission fluids contain phosphorus or zinc compounds that can pollute the sensors. The more transmission fluid you put, the greater the damage it can bring to your fuel system.

Some people use such kinds of fluid to lubricate and clean their car’s valve train. They do so by mixing a small amount of transmission fluid to fuel in gas tanks. While some people practice such a thing, it would be best to stay on the safe side and never put this fluid in your gas tank.

In this article, we’ll walk you through all the possible effects of transmission fluid if you or someone put some in your gas tank. This way, you’ll understand what happens, and you’ll know how to deal with such if it ever happens to you.

Without further ado, let’s get into it!

Table of Contents

What would happen if you put transmission fluid in a gas tank?

If you put transmission fluid in a gas tank, the fuel system can get contaminated, especially the oxygen sensors.

One thing to note about transmission fluids is that they may contain either phosphorus or zinc compounds. Either of these two compounds can cause contamination to the oxygen sensors found in the fuel system.

In short, the more fluid you put in the gas tank, the worse the damage it can inflict upon your system.

Some people use transmission fluid to clean the engine. However, gasoline also has detergents that can clean the engine more efficiently. Thus, it offers a safer solution if cleaning is your sole purpose.

Short term effects

The short-term effects of putting transmission fluid in a gas tank aren’t that noticeable. However, it can already cause minor damages to the engine, especially if you continue running your engine with such fluid in the gas tank.

As mentioned earlier, these fluids contain either phosphorus or zinc compounds. Either of these two compounds can cause contamination to the oxygen sensors found in the fuel system.

Thus, it would be best to have the fluid removed as soon as possible. Prolonged usage of the engine while having transmission fluid in the tank can lead to further damage.

Long term effects

If you keep on using transmission fluid in your gas tank, chances are you’ll eventually disable the entire engine.

The contamination it can bring to the oxygen sensor for long periods can eventually cause a disruption in the performance and the engine’s overall health.

As always, take it as a rule of thumb not to use such fluid in a gas tank. It would work well in your engine, but it can damage the fuel system and damage the entire engine system.

Can transmission fluid in a gas tank damage an engine?

Yes, transmission fluid in a gas tank can damage an engine. While some people would tell you that a small amount of transmission fluid won’t hurt the engine, it’s still best to stay on the safe side and avoid doing such.

The claim might be valid if you put some in the engine oil. However, it’s not the same thing with the gas tank.

The tank has oxygen sensors that can get contaminated. Since most transmission fluids have either phosphorus or zinc compounds, the fluid can pollute the fuel system. For this reason, you need to have it fixed as soon as possible should it ever happen to you.

How much transmission fluid in a gas tank will ruin it?

Even a small amount of transmission fluid in a gas tank can and will ruin your engine. If you put transmission fluid in a gas tank, the fuel system can get contaminated, especially the oxygen sensors.

In general, the more transmission fluid you put in the gas tank, the worse the damage it can inflict upon your system.

Transmission fluids can include phosphorus or zinc compounds, which is something to keep in mind. The oxygen sensors in the fuel system can be contaminated by any of these two substances.

Can you tell if someone put transmission fluid in your gas tank?

In reality, you can only tell if someone puts transmission fluid in your gas tank if it starts causing noticeable problems.

If someone puts transmission fluid in your gas tank, the fuel system can get contaminated soon. Such a problem can cause noticeable symptoms such as stalling, excessive smoking, and even disabling your engine.

Thus, if you think someone put transmission fluid in your gas tank, it would be best to shut the engine immediately and have it checked as soon as possible.

How to get the transmission fluid out of a gas tank?

If you discover that your gas tank contains transmission fluid, you must remove it immediately. It may, however, be a difficult task.

The first step is to turn off the engine and drain the gas tank. Later on, you’ll have to replace the gasoline filter.

It’s excellent if your gas tank has a gas cap or an entry from the trunk’s top. You’re allowed to peep inside if that’s the case. Some vehicles have it hidden behind the rear seat.

If this is the case, the transmission fluid can mix with the gasoline in the tank. Thus, you’ll have to drain the fuel out and replace it with a clean one.

Summary

In a nutshell, transmission fluid in a gas tank is not good for engines and fuel systems. The oxygen sensors may get polluted if transmission fluid is used in the gas tank. Phosphate or zinc chemicals, which are present in most brands, can contaminate the sensors. The more transmission fluid you consume, the more harm you do to your fuel system.

This fluid is used by some people to clean and lubricate their car’s valve train. This is achieved by mixing a tiny amount of transmission fluid with gasoline in gas tanks. While some people do this, it is recommended that you use caution and never put this fluid in your gas tank.

As always, be wary of whatever you put in the gas tank. Moreover, secure your garage and your car to prevent someone from putting anything in your gas tank.

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