Why Does a Manual Transmission Leak?


The fluid in a manual transmission is responsible for lubricating your gears. Metal-on-metal contact when fluid is missing causes wear, and a manual transmission run without adequate oil will damage quickly. Once your transmission is damaged, the only solution is to have it rebuilt or replaced, which is a costly and lengthy proposition. In the case of older vehicles, the cost of replacing a transmission or even simply physically repairing a leak can mean it’s not economically feasible.

If you have a manual transmission fluid leak and want to avoid costly repairs, you’ll be glad to know that at Bar’s Leaks, we have fast, affordable solutions that have been proven over and over again. Let’s look at why a manual transmission can leak, and what you can do to repair it before it becomes a major problem:

  • Gasket failure: This is the most common cause of manual transmission fluid leaks. The gasket creates a seal between your gearbox and your engine as well as your gearbox and the output shafts. The friction, pressure and heat generated in your transmission wear your gaskets and seals down over time, allowing fluid to leak. Most gasket and seal leaks start small and increase over time. Therefore, it’s important to inspect your transmission regularly for leaks. Look for transmission fluid puddling under your vehicle, traces of fluid around the seals and low fluid level on the dipstick.
  • Leaks at lines and connections: If your manual transmission has lines carrying fluid — to a transmission oil cooler, for example — you can also have leaks at the hoses or connections. Rubber hoses tend to get dry and brittle over time and can crack, allowing fluid to leak. Hose clamps can also rust and loosen over time and should be inspected regularly. They’re fast and easy to replace and can help avoid a major problem down the road. Tighten any fittings or connections you have access to, as they can also allow transmission fluid leaks.

It is extremely uncommon to have a fluid leak through the casing of your transmission. If you do, it is the result of a major impact or fracture and will require a major intervention. Thankfully, most transmission fluid leaks are easy to treat with one of our proven products. Our popular manual transmission fluid leak solutions include:


  • One Seal Stop Leak: A single application of our stop leak will seal your minor transmission leaks. You don’t need any automotive experience. You simply add the fluid to your transmission and let the formulation seal any leaks.
  • Transmission Repair: This product is designed to not only stop leaks, but also to take care of slipping and roughness in your manual transmission. We’ve spent over 60 years developing our unique formulas guaranteed to satisfy.
  • Stop Leak Concentrate: This concentrated formulation will make short work of your manual transmission fluid leaks. It is compatible with all types of transmission fluid, making your job easy. Simply pour it in per the instructions, and you’re back on the road in no time.

A leaking manual transmission doesn’t have to be a big problem. Trust Bar’s Leaks proven fluid repair solutions for your manual transmission at a fraction of the price of physical repairs.

Questions? We have answers. Hit us up on Facebook, or contact our support team directly. We’ll help with you with any concerns you might have.

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