How Can I Stop my Standard Transmission Leak?

manual transmission fluid leakStandard transmissions were the first kind of transmissions put into automobiles, and for a long time they were the only transmission option in a new car.  Even when automatic transmissions became popular in the 1950’s, a manual transmission was still the base, or standard option, hence the name.  Standard transmissions also called manual transmissions, 5-speeds or a “stick” are being ordered in fewer and fewer vehicles today as automatic transmission got more reliable, more efficient and less expensive.  In the 50s, about 80% of vehicles were sold with manual transmissions, while today, less than 10% of vehicles sold have manual transmissions, with many models not even being available with a manual transmission.

As with many things in life, manual transmissions have some benefits and some disadvantages over automatic transmissions.  Most of the benefits of a manual transmission are derived from its relatively simple construction and design.  A manual transmission only has 2 to 3 shafts inside each with gears riding on them.  The gears are already meshing, but ride on bearings on the shaft.  As you move the gear selecting lever, or the stick, you are choosing which set of gears will be coupled to the input and output shafts by sliding a collar on the shaft.  Different gears have different ratios which will affect the vehicle speed versus the engine speed.  These gears and shafts ride in a pool of gear oil which helps keep them cool and lubricated and is the source of the majority of the resistance in a manual transmission.

An automatic transmission on the other hand has multiple gears all on the different shafts and that can be free spinning, stationary or coupled to another set of gears.  This is accomplished by multiple clutches, bands and springs.  These are operated by high pressure automatic transmission fluid which requires a pump and many valves, hoses and small passages.  All of this equipment takes a significant amount of energy to run and leaves room for a lot of things to possibly go wrong or break.

Changing Manual Transmission FluidBecause of the simplicity of standard transmissions they often have the potential to outlast many other important parts of your vehicle, including the engine, as long as they are maintained properly.  The biggest thing you can do to keep your manual transmission in good working condition for years to come is to regularly change the transmission fluid.  Changing manual transmission fluid is often even easier than changing your engine oil because there is no filter.  First, find the drain and fill plugs.  It’s often a good idea to remove the fill plug first to ensure it is not frozen on and to check the fluid level before draining.  The oil should be just up to the bottom of the fill plug hole.  If it is lower, check the transmission for leaks at any gasket or seal points, where the axles or transmission exit the transmission housing at where the transmission bolts to the engine.  If your fluid level is good, remove the drain plug, let the transmission drain and replace the drain plug.  At the fill plug, add the factory recommended type of manual transmission fluid or gear oil until it just begins to run out of the fill plug.  Replace the fill plug and you’re done!

If you discovered a fluid leak in your manual transmission, you should seal the leak immediately.  Since manual transmission fluid level is difficult to check, a leak can lead to a low fluid level without you knowing causing permanent transmission damage and a costly repair bill.  To seal your leak easily and permanently, add BlueDevil Transmission Sealer with your new transmission fluid.  BlueDevil Transmission Sealer can stay in your transmission fluid and will not clog or harm anything.  BlueDevil Transmission Sealer will absorb into the old rubber seals in your transmission restoring them to their original size, shape and softness sealing your leak permanently from the inside out!

BlueDevil Transmission Sealer

You can purchase BlueDevil Transmission Sealer online, or from any of our authorized retails:

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

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31 responses to “How Can I Stop my Standard Transmission Leak?

  1. I like to say we used 3 H!!alf Gallon Bottles on a Head Gasket Leak on a 5.9L Cummins CNG (Natural Gas) Engine and the Leak has been Stop over 6 months Now. This Bus is Still Running at LAX Airport fine & has no Leaks

  2. I have a zf s6 40 manual transmission corvette uses synthetic oil for. Engine what sealer should I use? For engine or for transmission?

  3. I Have a 2007 Chevy Cobalt SS 2.0 with a 5-speed Manual transmission it recently started to Make a Whiny Noise when it’s in Neutral,. And When I’m Driving and go to put it in 3rd Gear it Grinds an gives me a hard Shift unless I double Clutch and rev it up a Bit? I don’t know what could be Wrong? Any Ideas?.

    1. Reyes,

      Thanks for your question about your Chevy Cobalt. It sounds like your 3rd gear synchro is worn out causing the grinding your experiencing while shifting. You could try changing your transmission fluid and adding a synthetic fluid with friction modifiers to see if that can get your transmission to last a little longer, but at the end of the day you’ll need to have your transmission rebuilt. The whiny sound you’re hearing could be an indication that a bearing in the transmission is also failing, or it could indicate your throwout bearing is getting worn out. When you have the transmission rebuilt you should consider having the throwout bearing (and probably the clutch) replaced as well since its an inexpensive part and easy to get to while the transmission is off.

      Thanks again for your question!
      -BD Auto Pro

  4. I have an older toyota truck with a manual trans that runs gear oil not trans fluid, is the blue devil ok to use for a small leak?

    1. Mason-

      Yes, you can use the BlueDevil Transmission Sealer for the leak you have described. You will be using one oz of the product per quart of fluid in the system.

      Thank you!


  5. I have a 2009 toyota corolla with a 5 speed. It just started leaking very little where the axle is. Will blue devil help this? If so which product should I use? Thanks a bunch

  6. I have a 1949 Lincoln with a 3 speed Overdrive transmission it started leaking a while back I think it’s leaking out the rear seal will your product work for me

  7. I have an 85 Pontaic Fiero and I am using GM synchromesh in the four speed manual transmission. I have a passenger side axle leak, pretty steady drip. What will stop the leak?
    And should I use a non synthetic fluid instead ?

      1. I have a Lincoln 2001 in its hard for me to put it in gear in its leaking transmission fluid can blue devil fix it

  8. I have a 95 Ford F150 5 speed manual trans with only 97,000 miles and when it gets to about 40 degrees and under, O have to put a couple ounces of dot 3 brake fluid in the reservoir a day. If the weather warms up to 45 degrees or higher, the reservoir stays full. What do you suggest I use? Thank you!

  9. I have a 5-speed transmission in my Mazda b2600i. It developed a leak from somewhere around or in the bell housing. The only seal close to that area is the input shaft seal and I replaced that. It continues to leak and no its not the rear main seal. I want to use a stop leak to hold back the seepage but I’ve heard that they can lessen the viscosity of the gear oil. On top of that, it causes the seals to swell, thus making them last for a shorter period of time. Is there a good probability that blue devil could restrain the leak for a good bit till I can get my tranny rebuilt?

    1. Bruce-

      Thank you for asking about your Mazda b2600i. Based on your description, we recommend using the BlueDevil Transmission Sealer ( to seal your transmission fluid leak. The BlueDevil Transmission Sealer would not affect the viscosity of the oil in anyway. Also, it does not harden or thicken, so it wouldn’t have any adverse affects on the system. 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!


  10. I have a Tremic TKO 600 with a very small leak from the main-tail section joint gasket. Will your product work on gasket leaks?

    1. M.B.-

      Thank you for asking about your Tremic TKO 600. The BlueDevil Transmission Sealer is intended to seal leaks coming from the rubber seals/gaskets/o-rings in the transmission system. As long as you are not losing fluid too quickly, you would be a great candidate for the product.

      Thank you!


  11. I have a 2009 Ford flex and it’s leaking transmission fluid. I put blue devil stop leak in it 6 days ago and I started seeing the smoke again let’s me know it has started back leaking. Can I use another can or just wait a lil longer for the sealant to work??

    1. Cynthia-

      Thank you for asking about your Ford Flex. Typically with the product, you would expect to see results after approximately 100-200 miles of driving. If you have driven the vehicle at least that much, and have noticed some kind of improvement, a second application would be recommended. Please contact our technical support line at 888-863-0426 so that we may assist you in receiving a replacement bottle.

      Thank you!


  12. I have a Tremec tko600 5 speed manual transmission with a leak where the tail shaft is bolted on to the transmission. The joint does not have a rubber gasket between the two housings it uses a liquid sealer applied between the two parts during assembly. Will your product work on this kind of leak? Thanks

    1. James-

      Unfortunately, the product would not work for the kind of leak you have described. The BlueDevil Transmission Sealer is only intended to treat rubber seals/gaskets. A hard part repair may be your best option.

      Thank you!


  13. Ok I just installed a new Tremic TKO 600 5 speed in my 77 vette and got just over 2,000. Mile on it and I’m leaking fluid on top of tranny. The rep, says it will only come out the vent if over filled and that us not the case, he says it might be a cover plate on top may need to be removed and resealed with gray silicone. If that cover is leaking a little or so will that stuff seal that or only restores rubber seal? Thanks Terry

    1. Terry-

      The BlueDevil Transmission Sealer would only have an affect on rubber seals/gaskets. Unfortunately, it would not be able to seal if the material is anything other than rubber.

      Thank you!


  14. I have a 08 Audi A4 Quattro. Has been leaking oil but i have no idea where it’s coming from. The leak was very slow and never lost very much oil. Took it to Wal-Mart and the guy said he couldn’t tell where the leak was coming from “up top” but he put a sealant around the plug. It’s now leaking more oil. What can i put in my car to stop the leak? I don’t have the money to take it to a mechanic. Please help!

    1. Angela-

      Thank you for asking about your Audi A4. Based on your description, we recommend using the BlueDevil Oil Stop Leak. The Oil Stop Leak is a universal application that would treat any of the rubber seals/gaskets in the system. As long as you are not losing oil too quickly, you would be a good candidate for the product.

      Thank you!


    1. Mike-

      Yes, the BlueDevil Transmission Sealer is safe and compatible to use for the application you’ve described. You will use one oz. of the product per quart of fluid in the system.

      Thank you!


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