Will Transmission Fluid Stop Rust? (Explained)

It is easy to lose your mind when you spot some rust on your car. After all, rust can significantly damage your vehicle by causing some parts to crack thus interfering with your safety as well as that of your passengers.

Rust is preventable. It can also be managed, provided it is identified in the early stages. This is more reason for you to always inspect your car every once in a while.

As a car owner, your first instinct when you see rust is to stop it from spreading and get rid of it immediately. Many products have been formulated for this purpose.

There are also DIY solutions that have been invented over the years and even though some are effective, not all will work to perfection. One of them is transmission fluid.

If you are part of various car forums, you have probably come across discussions on the effects of transmission fluid on rust. Some people claim that it works amazingly. And others will advise you to keep off it completely. What should you do?

Can I Use Transmission Fluid to Stop Rust?

Transmission fluid is oil like any other that is used to lubricate the moving parts in your car’s gear system.

It is no different from engine oil only that it has been specially formulated for the gears. That is the only role transmission fluid plays in your vehicle and nothing else.

This liquid is both a lubricant and a surfactant. It can’t remove rust. What transmission fluid can do for you is capture the rust on the surface and make it easier for you to wash it away.

Transmission fluid prevents rust from sticking to the surface. But it doesn’t remove it. The effects of transmission fluid on rust are very mild. And it can’t be compared to that of chemicals such as diluted phosphoric acid and the like.

Therefore, if you rush to use transmission fluid to remove rust spots on your car. Not only will you be disappointed by its lack of effectiveness.

But you will be wasting fluid that could have been used on your car’s transmission. Not unless you were using transmission fluid.

Does the Mixture of Transmission Fluid and Acetone Remove Rust?

By itself, transmission fluid isn’t strong enough to remove rust. However, when mixed in a 50/50 solution of acetone, it becomes a very powerful rust remover.

Acetone is the secret ingredient most people aren’t aware of. If you are dealing with rust on your car, and have some used transmission fluid in your garage.

Look for some acetone, mix it up, and apply it to the affected parts. You will be blown away by how effective this combination is.

Does the Type of Transmission Fluid Matter?

Not at all. There are two types of transmission fluids, one for manual cars and the other for automatics. Considering that this is a DIY application, the varying chemical composition hasn’t got anything to do with the effectiveness of rust removal.

If you use either, it will only remove surface rust. However, if you want to stop rust completely, you can mix either manual or automatic transmission fluid with acetone and let it do its job.

What are the Main Uses of Transmission Fluid?

At the beginning of this article, we were very clear that rust removal isn’t listed as an official use of transmission fluid.

This fluid is designed to lubricate gears, clean and protect the components of the transmission from wear, and increase rotational speed amongst others.

The origin of the claims that transmission fluid can be used to remove rust remains to be a mystery to this day.

And it’s surprising how many car owners opt to use it instead of actual ways that were designed and have been proven to remove rust on cars.

Why Does Rusted Metal Exposed to Transmission Fluid Come Out Looking Cleaner?

Did you know that some transmission fluids contain detergents? If you use one that has such a formula, it should be able to clean the hydrated iron oxide on the surface.

That is why when you expose the rusted metal to transmission fluid it comes out looking cleaner. But the truth of the matter is, that rust can’t be removed by transmission fluid. You should look for other alternatives.

Can Transmission Fluid Stop Undercarriage Rust?

Not unless you mix it with acetone, transmission fluid will do no such thing. And to make matters worse, the process of applying transmission fluid to your undercarriage is messy and time-consuming. There are better treatments out there that will have more desirable effects.

Any Safety Measures I Should Be Aware Of?

When handling a liquid such as a transmission fluid, you need to be very careful. Even though it is not described as a flammable liquid, it is combustible.

And that means it can catch fire. When using it to remove rust on your car, ensure that you wash it off as soon as you are done with the project.

If you risk leaving the transmission fluid in the undercarriage, the high temperatures at the exhaust can cause it to catch fire and that is a serious health hazard.

The second thing that you need to be careful about is the effect of transmission fluid on paint. Because it is made using strong ingredients, transmission fluid will hurt the car paint.

However, considering that you are dealing with rust on your car, paint shouldn’t be your biggest concern because it failed to do its job in the first place.

If the rust spots are on a particular section, avoid getting the transmission fluid to other parts as it will etch the paint after eating through the clear coat.

Are There Better Ways How You Can Stop Rust?

Surprisingly, many ways are far much better than transmission fluid, all of which can help you stop the effects of rust on your car.

We are going to list some of these options for you so that you can opt for a better method or product.

• WD-40

Being a product that is commonly found in most households, WD-40 is an excellent DIY rust remover. It is easy to use and very efficient.

To remove rust with WD-40, spray the multi-use product on the affected area and scrub with a brush. You should be able to remove the rust from your car.

The only downside of WD-40 is that it will remove some paint in the process, you will have to touch up or perform paint repairs.

• Scraping the Rust Stains

Using an electric sander, you can easily scrape off rust stains from metal. Even though this is an excellent DIY approach, we don’t recommend applying it on cars not unless you are dealing with an incredibly large area that has been exposed to rust.

Can I Use Chemical Rust Removers?

For rust that is proving stubborn to remove. Or if the metal has been corroded deeper, this is an excellent option. Chemical rust removers work fast and are very effective.

This is because they are made up using phosphoric acid which is known to have a very strong effect on rust. Depending on the chemical rust remover you are using, some may require to be applied and allowed to sit for a while.

Others you may have to spread it on the rusted metal and get to scrubbing. You must follow the instructions provided by the manufacturer to get pleasant results.

Instead of Transmission Fluid, Can I Use White Vinegar?

White vinegar is known to react with rust and dissolve it later on. Of course, you can use white vinegar. The problem is that it takes a very long time for it to remove rust on metal. Since time is something most of us don’t have anymore, this option isn’t one of the best.

What is the Best Undercarriage Rust Protection Solution?

If you live in a rust-prone area, you may be worried about your undercarriage being corroded by road salt. The best solution, in this case, is to prevent the rust from even forming on your undercarriage instead of waiting to stop it.

Most dealers offer rust protection packages where the undercarriage is sealed by a rubber coating that prevents the rusting process from being initiated.

At times these offers made by dealers don’t always have your best interests at heart. Dig deeper into what the treatment entails and whether there is a warranty.

You can also buy a rust-proofing spray and do it yourself. The best fighting chance you have against rust is to prevent it because once it occurs, you have a minimal chance of winning.

Out of the many ways you can deal with rust, transmission fluid should be your last option because as we have said, it cannot remove rust. Remember, you can always do a spot test and give us your feedback.

Products such as POR-15 do an excellent job of restoring vehicles that have been affected by rust. There are many others like POR-15, it is all a matter of preference.

The thing about DIY solutions is that they can be a hit or a miss. In this case, using transmission fluid to stop rust is a big miss.