While we are usually not a fan of additives, Lucas Transmission Fix deserves consideration if you are looking for a last resort to fix a bad transmission.

Problems that Lucas is supposed to fix:

  • Slipping
  • Whining, Humming
  • Leaking Seal
  • Hard Shifting
  • Shuddering

At least that’s according to Lucas Transmission Fix.

Lucas transmission fix is meant to be used when experiencing the above transmission problems. Lucas is one of the most popular transmission additives, and if you have transmission problems, you most likely have heard of it. Some may swear by this additive, even go as far as to call it “miracle fluid.” While in other cases, using Lucas transmission fix doesn’t make a difference.

Does Lucas Transmission Fix work?

lucas transmission fix

We have used this additive in several cars where the automatic transmission would experience slipping, rough shifting, or hesitations, with mixed results.

We have had mixed results with the Lucas transmission additive. There were times that Lucas’s transmission additive improved the shifting, and in other cases, it didn’t make a difference. When a transmission has electrical issues, Lucas makes no difference. If the problem is worn components inside the transmission, Lucas usually makes a difference. Getting a transmission shop to find the root of the problem is better than trying an additive.

Getting a transmission shop to find the root of the problem is better than trying an additive.

In some cases, the fix may be straightforward, and in other cases, it can be caused by electrical problems not directly related to the transmission. There are transmission additives that are designed for specific problems. You can read more about those alternatives at the end of this article.

Should I use Lucas Transmission Fix?

If you have just started noticing your transmission slipping, banging into gear, hard shifting, or seal leaks, don’t add Lucas. First, check the transmission oil level. 


If the transmission fluid level is low, you may experience transmission issues, such as transmission slipping, hesitation, shuddering, banging into gear, and more. It doesn’t mean you need a new transmission. You would be better off topping the transmission once in a while than adding additives to your transmission. Perform a transmission fluid and filter change. A clogged transmission fluid filter can cause all the problems mentioned above. To eliminate that possibility first.

When to Try Lucas Transmission Fix

If your mechanic recommends that you need your transmission replaced, then it is time that you try the Lucas Transmission Fix.

A transmission additive can, in certain cases, extend the life of the transmission. When using Lucas Transmission Fix, we have cases owners have been able to get another year or two out of the transmission. Your transmission will eventually require transmission to be properly repaired or even overhauled.

It is important to get your car diagnosed by a mechanic.

You should not continue to drive your car if the transmission is starting to act up. Get it diagnosed ASAP. In some cases, the problem may be something as simple as oil leaking into the electrical connector or replacing the valve body. The valve body can be replaced in many cars without removing the transmission. Either way, you should address transmission problems as soon as possible to avoid further damage.  Lucas Transmission Additive can extend your transmission’s life, but only if you use it before severe damage occurs.

Read What People Say About Lucas Transmission Fix

When to use Lucas Transmission Fix?

Before we answer the question, Does Lucas transmission fluid work, we need to understand what Lucas additive is designed to do.

Lucas Transmission Fix is a non-solvent formula designed to mix with your transmission fluid to stop slip, hesitation, and rough shifting in worn transmissions and eliminate seal leaks.

Lucas Transmission Additive is designed to1:

  • Eliminate Transmission Hard Shifting
  • Stop Transmission Rough Shifting
  • Stop Transmission Slipping
  • Eliminate Seal Leaks

The Automatic Transmission Fluid (ATF) serves several critical functions. It regulates the solenoid’s pressure and allows shifting; it reduces gear wear, transfers heat, and transfers rotation via the torque converter. Over time seals in your transmission wear out, thus allowing transmission fluid to pass the seal and leak.

Even though the seal prevents the leak with time, it can harden and stop blocking leaks that it used to block when it was soft and new. Lucas Transmission Fix additive would penetrate the seals and soften them up a little bit. Also, Lucas additive will cause the seal to swell some to compensate for any wear and stop the leak.

Do Lucas Stop Leaks?

In our experience, Lucas Transmission Fix can stop seal leaks as long as they are small leaks. Once the leak becomes major, Lucas Transmission Fix will only slow down the leak but will not stop it. Remember that while Lucas Transmission Fix will stop small leaks, this repair will not last forever. You may notice the leak comes back in a few months or after a year, depending on the leak’s severity. To properly fix this problem, the worn-out seals must be replaced to eliminate transmission leaks.

Transmission Slipping, Rough Shifting, or Hesitation

In most cases, the transmission slips due to a clogged valve body, worn band, or bad torque converter.  Lucas can be useful in freeing up any worn transmission valve body solenoids. It also has friction modifiers that are added to renew transmission bands.

While the Lucas additive can improve the friction between clutch plates, it can not restore worn-out transmission bands. If the transmission is in the early stages of damage, adding Lucas may extend the transmission life unless the damage has become severe.

Why is Lucas Transmission Fluid so thick?

When you add the Lucas Transmission Additive to your transmission fluid, you will notice that it is quite thick and takes a while to come out of the bottle. Lucas Transmission Additive is so thick that it is meant to mix with your transmission fluid.

It is best to add the fluid when the transmission fluid is warm. It is important not to overfill the transmission. We have found that many 10 or 15-year-old cars may be on the low side of transmission fluid level, so you may be able to add Lucas without removing any fluid from your transmission.

Always check the transmission fluid and make sure not to overfill the transmission. If the maximum transmission fluid, you should remove about half a quart and add Lucas transmission additive. You can extract some of the fluid using a  Liquid Transfer/Siphon Hand Pump via the transmission dipstick tube.

Should I add Lucas when changing the Transmission Fluid?

Have you been recommended to add a quart of Lucas Transmission Fix when doing a fluid change?  Unless you have been experiencing rough transmission shifting, hesitation, or slipping, we don’t recommend that you add Lucas additive.

If you are looking for an additive that will reduce the transmission fluid’s operating temperature or make your shifting smoother, we recommend  Lubegard Automatic Transmission Fluid Protectant. It is designed to provide long-term wear protection. Simultaneously, it does not affect the newer electronically controlled transmission components, such as the multiple solenoids and sensors inside the transmission.

Lucas Transmission Fluid Alternatives

Lubegard Dr. Tranny Instant Shudder Fix 

This is a concentrated friction modifier. Can fix transmission problems related to torque converter shudder. Do not use on Ford Type F or CVT transmissions.

ATP AT-205 Re-Seal Stops Leaks

The ATP Reseal is designed to stop transmission seal leaks. If you have a squeaking noise, you can even spray the ATP AT-205 Re-seal on any rubber suspension bushings. It can be added to synthetic oils, gear oil, power steering fluid, and transmission fluid. It is worth trying if you like to buy time until you get the seal leaks properly repaired.  Remember that this will not fix a major leak or a damaged seal.

Sea Foam TT-16 Transmission tune Additive

If your problem is sticking the valve body, this is a good alternative to Lucas Transmission Fix. If you are looking for an additive that will not swell the seals and change the transmission fluid’s viscosity, you may want to look at the SeaFoam Trans Tune. We recommend you do an automatic transmission fluid change once your transmission is back to shifting smoothly. Usually, you should see shifting improve after a few hundred miles.

How do you use Lucas Transmission Fix?

  1. Before you add Lucas transmission additive to your transmission, it is important to check the transmission fluid level. You should not overfill the transmission with fluid. Siphon out as much automatic transmission fluid as you plan on adding from the additive. If you add half a quart of Lucas Transmission Fix, remove that much oil from your transmission. If your car is over 10 years old, check the fluid level, it may already be below, and you may not have to remove any fluid.
  2. Warm up your car by driving it around the block for ten minutes.
  3. Open the hood and find the transmission dipstick on your car. In most cases, the transmission dipstick is yellow. If you are not sure which one is the transmission dipstick, look in your owner’s manual. You don’t want to add Lucas additive to your engine oil.
  4. Use a long funnel to add the Lucas Transmission Fix fluid. You will notice the fluid flows very slowly due to its high viscosity. Take your time to add Lucas transmission additive. Do not add Lucas transmission additive more than the maximum transmission fluid level indicated.
  5. Next, you need to measure the transmission fluid level.
  6. Warm up the car by letting it idle in Park for 10 to 15 minutes. Now recheck the transmission fluid level. If the level is low, add more fluid. You need to remove some fluid if it is above the high mark. A transmission should not be overfilled with fluid. 
  7.  Drive your car around the block for 20 to 30 minutes to allow Lucas’s additive to dissolve with your ATF fluid. As you drive around, manually shift the transmission through the lower gears by placing the gear selector lever in the 1, 2,3, D, and R positions.


Before adding additives, you should always check the transmission fluid level and add the recommended automatic transmission fluid (ATF). The correct trans fluid for your car is listed at the end of the owner’s manual.

“Our test data show some additives can provide a brief improvement in, for example, anti-shudder durability, but it’s short-lived, and performance quickly drops below industry standards,” said Matt Erickson, AMSOIL Product Manager, Passenger Car.5

Lucas Transmission Fix may be worth trying if your transmission has started to slip, delay shifting, bang into gear, shutter, or leak oil. Lucas additive is not going to fix every possible problem out there.

We don’t usually recommend additives, but if you have been told that your transmission needs to be replaced, it doesn’t hurt to try Lucas Transmission Fix. You may be one of the lucky people Lucas Transmission Fix can help, at least for the time being.

While there is no guarantee that Lucas transmission fix will work if you have been quoted a transmission overhaul, what do you have to lose?

Read What People Say About Lucas Transmission Fix

Our friends at Project Farm did in-depth testing of Lucas’s transmission fix. Make sure to watch the last three minutes of this video. Remember that no transmission additive will fix the automatic transmission problems if broken internal parts or bands have burned out.


  1. Lucas Transmission Fix Product Details Lucasoil.com
  2. Is Lucas Transmission Fix OK to use? cartalk.com
  3. Data Sheet – Lucas Transmission Fix
  4. Safety Data Sheet
  5. Do transmission fluid additives work? AMSOIL.com

We hope you find the Lucas Transmission Guide helpful. Check these troubleshooting and repair guides for more help on your vehicle.

Leave a Reply

Your email address will not be published. Required fields are marked *