Automatic Transmission Leaking Oil
Fix Leaks with an Additive

If your automatic transmission is leaking oil or the transmission housing is covered with oil, the cause is usually aged or hardened seals. Due to heat and pressure, these seals lose their sealing ability over time. With LecWec, you can restore the sealing effect directly during operation without removing or dismantling the transmission.

✓Oil leak stop for automatic transmissions
✓Long-lasting sealing effect for many years
✓Oil sealing additive without chlorine
✓Seal the transmission without removal

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How LecWec Works in Automatic Transmissions

Automatic transmissions use polymer seals at shafts, valves and housing connections to keep the ATF fluid inside the system. Due to heat, pressure and aging, these seals lose elasticity over time. The result: transmission fluid begins leaking from sealing points or pressure loss occurs inside the system. This is exactly where LecWec works during normal operation.

After being added, LecWec blends with the transmission fluid and distributes throughout the entire system. The active ingredients are absorbed by the seals and help the material become flexible, supple and tightly sealing once again. This closes the fine gaps between the seal and the metal surface.

In practical use, this means that oil leaks from the automatic transmission are greatly reduced or stopped completely. LecWec restores the sealing function of the existing components without affecting the operation or shifting characteristics of the transmission.

Only 3% of the total oil quantity.

LecWec is chlorine-free.

For all oil systems and types.

Direct delivery from the manufacturer.

It happened even faster than I expected.

"I have to report positively that the level matches the oil... unbelievable. [...] I wouldn’t have believed that the steering gearbox would be sealed again after just under a week."

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"...nothing was leaking anymore!!! I am truly very satisfied. At first, I did not believe the product would work, but now I am completely convinced and also saved many hundreds of euros!"
- Jürgen R.

Oil leak at the cylinder base gasket

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"I did not believe it at first, but your product is excellent! [...] I ordered just one can and everything is sealed already, even though you recommend 2 cans, meaning 200 ml, for 6 liters of oil. Many thanks!"
- Andreas F.

Oil leak problems at the oil flange gasket

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"...which made it even more satisfying when, after around 3 weeks, I noticed that the oil loss had gone down to zero – the steering rack was sealed again!! Even now, after 4 months, the reservoir is still at the maximum level."
- Friedger F.

Oil leak at the steering rack

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"There was always a small puddle of oil collecting underneath the vehicle. I added 100 ml of LecWec to around 4 liters of oil. Since then, I have driven many miles and was surprised to find that there was no more oil on the ground at all."
- Paul R.

Leak at the oil pan

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How to Seal an Automatic Transmission in 3 Steps

If your automatic transmission is leaking oil, this is usually noticeable through oil spots underneath the vehicle, oil-moist transmission housings, or a dropping fluid level. The cause is usually aged polymer seals. Instead of removing the transmission, you can address the issue directly within the system.

Step 1: Check the fluid level and determine the total volume of ATF fluid.
Step 2: Add LecWec directly to the transmission fluid at a ratio of 3% of the total oil volume.
Step 3: Drive the vehicle normally – the additive will circulate throughout the entire transmission system.

The seals absorb the active formula, become flexible again, and fit tightly against the sealing surfaces once more. This stops oil leaks at the affected areas. You avoid removing components and restore the automatic transmission to a sealed operating condition.

Automatic Transmission Leaking Oil? These 5 Tips Can Help

Identify the exact leak location
Clean the transmission housing thoroughly and check where the oil is leaking after a short drive. This helps avoid unnecessary repair work.

Check the fluid level correctly
A fluid level that is too low or too high can cause problems. Check the ATF level exactly according to the manufacturer’s specifications.

Inspect sealing points directly
Typical weak points are shaft seals, transmission pan gaskets, and housing connections. These are often the first locations where oil leaks occur.

Restore seals directly
Automatic transmissions use polymer seals that harden over time. Through targeted treatment within the system, the sealing performance can be restored.

Use LecWec correctly and monitor the results
Add LecWec to the system at a ratio of 3% of the total oil volume and drive the vehicle normally. Afterwards, check the sealing performance. In many cases, the oil leak is significantly reduced or completely stopped.

Questions and Answers about LecWec

How Does LecWec Work?

Replacing a leaking oil seal is usually not an inexpensive repair. If an entire component needs to be replaced, the costs increase even further. Since 1995, however, “LecWec” has provided a permanent repair solution for polymer oil seals without disassembly or replacement, and without major time or repair costs. LecWec is not only effective for vehicles, but for all oil systems and all types of oil. Over time, polymer oil seals lose their plasticizers, become brittle, and shrink. LecWec impregnates the seal material and replaces the lost plasticizers. The seal becomes flexible again and expands slightly – exactly enough to compensate for wear at the sealing lip.

3How Much LecWec Do I Need for My Automatic Transmission?

The required amount of LecWec depends on the total ATF capacity of your automatic transmission. The dosage is exactly 3% of the total oil volume. For a transmission containing 9 liters of ATF, this equals 270 ml of LecWec. The additive is added directly into the oil circuit and circulates throughout the entire system during operation – including the torque converter and valve body. This allows LecWec to reach internal sealing points without requiring transmission disassembly.

How Long Does It Take for LecWec to Work?

LecWec does not work instantly but requires a certain amount of operating time to take full effect. After application, the engine should initially run for some time so the product can circulate through the system and reach the affected seals. The effect then continues to develop during further operation and also during periods of inactivity. In many cases, the desired sealing effect becomes noticeable after around 200 km of driving. Depending on the condition and material of the seals, however, it may take several days for the full effect to develop. Once this process is complete, the sealing performance remains stable over the long term and can last for years.

How Long Does the Effect of LecWec Last?

The effect of LecWec is designed for long-term sealing performance. Once the product has fully developed its effect, it usually remains effective for years. The requirement is that the product has enough time to circulate through the system during operation and fully interact with the seals. For this reason, the engine should initially run for some time, after which LecWec continues working through normal operation and even during periods of inactivity. Depending on the seal material, this process can take anywhere from a few hours to several days. Once the full effect has developed, LecWec keeps the seals flexible and leak-free permanently without requiring regular reapplication.

3How Reliably Does LecWec Stop Oil Leaks?

LecWec stops oil leaks reliably and almost completely when the leak is caused by aged or hardened seals. The active formula circulates through the oil system and reaches all relevant sealing points. During operation, the seals absorb LecWec, become flexible again, and expand slightly. This allows them to fit tightly against the sealing surfaces once more and close the fine gaps through which oil previously escaped. Depending on the application, the effect begins within a few hours to several days and then remains stable over the long term.

3When Does LecWec Not Work?

The effect is limited on cork and paper gaskets. These rarely used materials can only absorb LecWec to a limited extent. In practical use, slight swelling may occur, which can reduce minor leaks. However, complete sealing of cork and paper gaskets cannot be achieved reliably. LecWec also does not work directly on metal gaskets, since these materials have no elasticity. If the oil leak is caused by adjacent polymer seals or minimal gaps, LecWec may still contribute indirectly to sealing the system.

3Do I Need to Disassemble the Automatic Transmission?

No. LecWec is added directly to the transmission fluid and works during normal operation. Disassembly of the automatic transmission is not required, provided the oil leak is caused by aged seals or shaft seals.

5Does LecWec Also Help on Older Automatic Transmissions?

Yes. Especially on older automatic transmissions, shaft seals and sealing lips are often hardened or shrunken. LecWec restores the elasticity of these seals and can significantly reduce typical leaks at shafts, housings, and connections.

6Does LecWec Help with the Torque Converter and Valve Body?

Yes. LecWec can help with leaks in the area of the torque converter, valve body, and internal seals, provided the cause is aged sealing lips or O-rings. In cases of mechanical wear or defective valves, the effect is limited.

6Can LecWec Also Be Used Preventively?

Yes, LecWec can also be used preventively to keep seals flexible over the long term. Especially in vehicles with high operating hours, the application helps prevent seals from drying out and becoming brittle. For preventive use, a reduced dosage of 1.5% of the total oil volume is recommended. This keeps the seals elastic and significantly reduces the risk of future leaks.

Can LecWec Damage the Engine or Transmission?

No. LecWec is developed to fully blend with the existing oil without affecting lubrication performance. It does not attack metal components and does not alter system tolerances. Bearings, gears, and other components remain completely unaffected. LecWec works exclusively on the seals within the system. When used correctly and at the proper dosage of 3% of the total oil volume, the application is safe and has no negative effect on the function of the engine, transmission, or hydraulic system.

8How Much Does LecWec Cost and Where Can I Buy It?

You can buy LecWec directly online in our online shop. There you will also find all current prices. Alternatively, you can send us a message below and we will gladly help you with your question or order.

+49 89 - 90 35 638

Monday - Friday
9:00 AM - 5:00 PM

order@lecwec.de

Automatic Transmission Leaking Oil Fix Leaks with an Additive

How LecWec Works in Automatic Transmissions

Only 3% of the total oil quantity.

LecWec is chlorine-free.

For all oil systems and types.

Direct delivery from the manufacturer.

It happened even faster than I expected.

How to Seal an Automatic Transmission in 3 Steps

Automatic Transmission Leaking Oil? These 5 Tips Can Help

Questions and Answers about LecWec

Automatic Transmission Leaking Oil
Fix Leaks with an Additive