Best Transmission Leak Sealer In 2024

Having a leak in your transmission is quite annoying.

When it happens, you will see oil drips here and there, and you will lose 3 quarts of oil per month at least.

There will be a lot of expensive and frustrating problems if the transmission fluid goes too low.

It causes higher transmission temperature and makes the friction components wear faster.

You may seriously damage your transmission if you keep driving with a low fluid level. Therefore, you should stop the leak as soon as possible if you want to maintain your vehicle in good condition.

To solve the transmission leak problem, you must choose carefully. There are dozens of products for different oil leak problems, but most of them are not professionally designed for transmission leaks.

They may be helpful but are not very effective.

The reason is that the rubber parts in transmissions are different from those in other oil systems. They need different components to get restored.

If you want to get the best performance, here are 5 products we highly recommend.

They are fast, convenient, and good value for money. These 5 products are the best transmission leak sealers on the market, and you should have one around the garage in your car.

best transmission leak sealer

1. ATP Automotive Re-Seal – The Best Transmission Stop Leak Product

ATP Automotive is the best transmission leak sealer that performs well and can be used for stopping other leaks.

It works quickly and effectively in stopping all leaks in the transmission.

We also it for its value for the dollar.


How to use a transmission leak sealer?

As discussed above, a transmission leak sealer is a product that is designed to stop leaks in a transmission.

It can be used in an emergency situation or as a preventative measure.

To use a transmission leak sealer, first identify the source of the leak. Once the source has been identified, clean the area and ensure that there is no more liquid coming out.

Now you can apply the leak sealer directly to the leak.

Note that you need to allow the sealer to dry completely before driving the vehicle. If you don’t, then you’ll be back to square zero.

By the way, there are some leak sealers that require you to start your car and leave the leaking circuit to heat up. You may not be needed to drive in this instance.

The best way to be sure in this instance is to read the indications.

What is the Best Transmission Stop Leak Sealer

1. ATP Automotive Re-Seal Stops Leak

best transmission leak sealer

When you notice that your car has a transmission leak, it may not be the only problem.

Damaged parts in engines, power steering, differentials, and hydraulic systems may also cause leaking problems.

You need something to stop the leak and prevent other kinds of leaks in the future.

We recommend ATP AT-205. It is the best transmission oil stop leak in terms of performance. ATP AT-205 can quickly stop transmission leaks.

According to our tests, ATP AT-205 completely stopped the leak after driving about 800 miles.

It restores all rubber seals and gaskets in the transmission and brings them back to their best conditions.

ATP AT-205 also helps to prevent future leaks. It works not only in transmissions but also in engines, power steering, differentials, and hydraulic systems.

It restores all rubber parts just like it has done in transmissions. ATP AT-205 is compatible with most kinds of oils on the market. So, it performs the same in different oil systems and does no harm to components.

It’s easy to use ATP AT-205. When you are going to do the oil change, drain some waste oil and pour a full bottle in.

Let it circulate in the system, and usually, you will find that the leak stops after a total of 5 hours of driving.

The product may not work if the leak is caused by metal parts. In that case, you can call the manufacturer for further help.


2. Lucas 10009 Transmission Fix

best transmission stop leak sealer

Lucas is one of the most well-known producers of transmission leak sealers.

They produce dozens of products for different oil leaks. The Lucas 10009 is the best transmission oil leak stop additive in their lineup. As we investigated, Lucas 10009 solves most of the transmission leak problems, and it has been widely approved by its customers.

Lucas 10009 is quite popular because it stops transmission leaks fast.

The transmission leaks are usually caused by dried-out, harden, or shrunk rubber parts in transmissions. Lucas 10009 can quickly restore them and bring them back to their best conditions.

In this way, it stops the leak permanently and also prevents future leaks.

Lucas 10009 is also easy to use. It is suitable with all kinds of oils, so you don’t have to drain any fluid before adding Lucas 10009. It contains no solvents, so it’s harmless and you can use it in most kinds of oil systems.

You can’t be wrong if you follow the instruction. Add a full bottle of the product, and you will get a no-leak vehicle after a few hours of driving. You should do it every 5000 miles, so it will prevent leaks in the future.

Sometimes Lucas 10009 doesn’t work because the vehicle is too old to fix. I

t can’t restore the torn metal parts or the rubber parts which are broken into pieces. In this situation, you should take your vehicle to the garage and let skilled workers fix it.

We can’t ask for more since Lucas 10009 is just a cheap solution for transmission leak problems.

But we can get a lower price if we buy it by the dozens. It won’t waste your money because you will use it very often as a good measure of daily maintenance.


3. BlueDevil Transmission Sealer

best transmission stop leak additive

If you are familiar with transmission leak sealers, you must know BlueDevil Products.

It’s well known as it has produced dozens of products for all kinds of oil leaks. Most products of this company are proven to be effective, and BlueDevil Transmission Sealer is the best transmission leak sealer of BlueDevil Products.

BlueDevil permanently stops the leak in transmissions.

The dried, cracked, and shrunken rubber seals will be restored by BlueDevil, and they will no longer cause transmission leaks. It works in manual or automatic transmissions. You will see the difference after using no more than two bottles of the product.

Otherwise, it is a leading indicator that you have serious problems with your transmission. In that case, you should ask the manufacturer or some skilled worker.

If your transmission doesn’t leak, you can also use BlueDevil to prevent future leaks.

You don’t need to worry because it doesn’t harm the transmission or any other parts of the oil system.

To get the best performance, you should add a full bottle of the product to the oil right before the oil change. It will restore rubber seals and gaskets after circulating in the oil system.


4. Motor Medic Automatic Transmission Sealer

transmission stop leak additive

Motor Medic M1432 is the best transmission oil leak stop provided by MotorMedic.

The company is well known because of the good quality of its products. Just like other MotorMedic products, Motor Medic M1432 is reliable and convenient.

It works great in stopping transmission leaks, and it’s helpful to prevent future leaks.

Motor Medic M1432 does a great job with transmission leaks. Like its competitors, Motor Medic M1432 restores rubber parts that are dried, harden, or shrunk.

It performs the best when working on the seals and gaskets in transmissions. It may not be effective if the leak is caused by torn metal parts.

You should carefully check your transmission before using this product, or it would be a waste of money.

Motor Medic M1432 is convenient. All you need to do is add it right before the oil is changed.

The leak will be stopped after several hours of driving. It won’t damage your transmission, and you can mix it with any other kind of oil. Finally, Motor Medic M1432 is quite cheap. It’s definitely worth a try.

It’s not a big deal if it fails to stop the leak as it can still prevent future leaks.


5. Bar’s Leaks Transmission Stop Leak

Bar’s Leaks 1420 may be one of the best transmission stop leaks on the market.

It may not be as effective as other professional products, but it performs well when solving transmission leak issues.

Bar’s Leaks 1420 restores gaskets and seals to stop transmission leaks. Usually, it takes an hour to completely stop the leak. The bad thing is, its performance is extremely fast but not very stable.

This product is specially designed for transmissions, and it may do nothing if the rubber parts are not suitable.

It sometimes fails when working on super old cars. We advise you not to use Bar’s Leaks 1420 as the first attempt to fix old leaks. You should use it as weekly maintenance for your transmission.

To get the best performance, you should read the instruction or call the manufacturer before using Bar’s Leaks 1420. If your transmission is suitable, the product will work well and fast.



In conclusion, ATP Automotive Re-Seal Stops Leak, Lucas 10009 Transmission Fix, BlueDevil Transmission Sealer, Motor Medic Automatic Transmission Sealer, and Bar s Leaks Transmission Stop Leak are all great options for repairing a leaky transmission.

They are all easy to use and will stop the leak quickly. So you are safe to use any one of the above seals.


The Review Gurus