How Can I Seal a Transmission Leak?

Checking Transmission FluidHaving a leak in your transmission can be a dangerous thing. It may seem like a few drips here and there won’t end up being a problem, but let’s do the math.  Assuming the puddle is big enough for you to notice, let’s say a puddle about the size of a dollar bill overnight, your transmission would lose about a quart of fluid every 10 days.  If your transmission holds 4 quarts of oil in the pan, then that’s a quarter of your fluid capacity gone in 10 days, and almost all of it gone in a month!

Having low transmission fluid can cause a lot of  expensive and frustrating problems.  First, the lack of fluid can cause higher than usually transmission temperatures.  The fluid in the transmission helps car heat away from friction points.  Less fluid means a higher temperature and a reduced capacity to cool the friction components allowing them to wear faster and potentially fail sooner.  An inadequate transmission fluid level also can mean poor lubrication if there is not enough fluid to reach the critical areas of the transmission also causing premature wear.  Lastly, a low transmission fluid level can cause dangerous drivability issues for your vehicle.  Transmission fluid is the high pressure operating fluid that cause gear smooth and accurate gear changes.  A low level can allow your vehicle to behave unpredictably and possibly even dangerously.

If you maintain your vehicle well and notice the transmission fluid leak, you may consider continuing to top of the transmission fluid level ensuring you don’t end up damaging your transmission due to a low fluid level.  Transmission fluid can range from 8$ a quart up to $15 a quart or more, so every 10 days you’re having to spend that much in replacement fluid, not to mention the time it takes to fill and check your fluid level every few days and continue to go to the auto parts store to purchase more fluid, funnels and clean up materials.

Transmission LeakThe most common leak points on automatic transmissions are the input and output shaft seals.  There is a shaft on the front of the transmission that slides either into the clutch plate or the torque converter that has splines on it.  This shaft transfers power from the engine to the gears in the transmission and will have an oil seal around it.  The output shaft similarly will have a seal that goes around the shaft, a slip yoke or the CV axles depending on the type of vehicle.  As these shafts or axles spin while your drive, over time they can start to wear down the seals around them.  Also, old fluid, low fluid or a lack of driving can cause these seals to dry out, harden or crack causing leaks.


Replacing these seals can often be a costly venture, and depending on the age of your vehicle and how long you intend to continue driving it, it may not be cost effective to replace them entirely.

You do however have another option.  Add BlueDevil Transmission Sealer next time you top off your automatic transmission fluid.  BlueDevil Transmission Sealer is specially formulated to restore the seals on the input and output shafts of your transmission to their original size and soft condition to permanently seal your transmission leak.  BlueDevil Transmission Sealer is guaranteed to seal your transmission leak!  Depending on the speed of your transmission leak BlueDevil Transmission Sealer can pay for itself in 2 weeks or less by saving you money on replacement transmission fluid.

Pick up BlueDevil Transmission Sealer today at your favorite auto parts store like:

  • AutoZone
  • Advance Auto Parts
  • NAPA
  • O’Reilly Auto Parts
  • Bennett Auto Supply
  • CarQuest Auto Parts
  • Pep Boys
  • Prime Automotive Warehouse

Or, purchase BlueDevil Transmission Sealer directly from BlueDevil here.

Pictures provided by: and

Related Posts

20 responses to “How Can I Seal a Transmission Leak?

        1. Devan-

          Yes, the BlueDevil Transmission Sealer would work to seal the leak you have described. You will not need a whole lot of product based on the small capacity. You should add 1 ounce of BlueDevil per every 1 quart of capacity. Expect to notice results after about 100 miles of driving.

          Thank You!


          1. Tee-

            It is very important to follow all of the directions properly to ensure best results. Using the full bottle will not harm your vehicle but you may want to siphon some of the fluid down and refill with the factory recommended transmission fluid.

            Thank you!


  1. Will this work in Manual Transmission (2007 Ralliart Colt) ? I have a very small leak on my input shaft seal (100ml every 6 months). Currently running Redline 75W90. Does it thicken the fluid at all ?

    1. Shane-

      The BlueDevil Transmission Sealer does not harden or thicken in any way. You should add 1 ounce of BlueDevil per every 1 quart of capacity.

      Results should be noticed after about 100 miles of driving.

      Thank You!


  2. Out of interest. Does this have any effects on cracks in the transmission casing? As in the metal? Thanks

    1. Robert-

      Unfortunately, the BlueDevil Transmission Sealer would not have any effect on an actual crack in the system. The product is specifically intended to rejuvenate and slightly expand rubber seals/gaskets.

      Thank You!


    1. Glenda-

      Yes, you may add the recommended amount (1 ounce of BlueDevil Transmission Sealer per 1 quart of capacity) of BlueDevil first and then top the transmission fluid to the proper level. You can expect to notice results after about 100 miles of driving.

      Thank You!


    1. Cindy-

      Once the product is added you will not start to notice results until the vehicle has been driven about 100 miles. Be sure you are using the correct amount, you should be adding 1 ounce of BlueDevil to every 1 quart of fluid capacity.

      Feel free to contact us at 888-863-0426 with any questions.



  3. I Have a trans leak caused by bushing wear in my 2004 cad deville.Tech says it needs third clutch housing replaced($1600)
    Friends told me about Blue Devil for head gaskets.Will your trans sealer correct my problem

    1. Sonny,

      Thanks for your question about your Cadillac Deville. If your leak is still just a dripping leak for a gasket or seal then BlueDevil Transmission Sealer will restore the seal and stop your leak. You need to make sure to replace the worn bushing to get everything back into alignment before you try to seal your leak.

      Thanks again for your question!
      -BD Auto Pro

  4. I have a 97 Ford Taurus I don’t see a Leck or anything but it takes a long time to catch gear I already put 4 bottles of transmission fluid in it

    1. Dwayne-

      The best place to start would be to change your transmission fluid and filter and then double check to make sure the fluid level is correct. Having the transmission fluid level too high or too low can cause the transmission to act up and not shift properly.

      If you are still experiencing the hard shifting after changing the fluid and filter and topping to to the proper level then you may want to have your Taurus looked at by a transmission specialist.



  5. Hello I have a 2002 Hyundai elentra. I have a transmission leak and was told that I needed to have my seal replaced. Sometimes I have a puddle of transmission fluid and other times there are just drops. It drives okay. Bt I have felt my car drive like it was dragging then it will jump real hard into gear then drive perfectly fine. I was wondering if I could add the blue devil sealer to fix the problem to my car ?

    1. Ashley-

      Thank you for asking about your Hyundai Elantra. Based on your description, we would recommend using the BlueDevil Transmission Sealer. You will be using one oz of the product per quart of fluid in the system and should expect to see results after about 100-200 miles of driving.

      Thank you!


Leave a Reply

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