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When you walk down the aisle of your local auto parts store, you’ll see products that claim to solve all your transmission problems. Many companies advertise that their transmission additives can unclog filters, smooth gear shifting, fix leaks, improve your horsepower, and extend the life of your transmission. Some even claim to be mechanics in a bottle.

Sounds too good to be true, right? Well, you’re correct. Such claims are generally untrue and can actually harm your transmission in the long run.


Transmissions, like anything else, can, and do wear out. A major victim of wear are the internal seals, which harden and crack over time. A hard seal cannot contain the pressure behind it and can cause shifting delays and leaks. Transmission fluid without additives works to prevent this by lowering friction and heat. Additives work differently. Additives in transmission fluid soften those seals so they can work effectively again.

Additive companies also claim to fix gears that have been stripped by wear and improve shift feel. This is accomplished by lubricating parts, so the parts simply slip past each other. Additives make you think the problem is fixed, but in reality it’s making rough or broken parts slide past each other. It doesn’t actually fix the problem.


While it may seem like a good idea to lube broken parts and soften hard seals, these additives are ineffective as long-term fixes. The additives that lubricate often break down under high heat, making gears and parts more prone to friction and heat damage.

In addition, the chemicals used in additives will cause your internal seals to continue softening until they eventually break down entirely. Once this happens, your transmission fails and your car will require some major and expensive repair.

Additives are a short-term solution to a long-term problem. It took many, many miles to wear out the parts in your transmission. A simple bottle won’t fix it.


What is true in other parts of your life is also true for your transmission—prevention is the best medicine. Regular maintenance is far more effective than resorting to transmission additives. Make sure your transmission always has enough fluid and that the fluid is changed when dirty. And always take your car to a professional whenever you notice a problem such as slipping, smoke, and noise.

It’s also a good idea to read your car’s owner’s manual, just in case your car has been designed to take a certain type of transmission fluid. For example, some cars function better with synthetics. It’s also a good idea to find a brand and stick to it, as different brand’s formulations can cancel each other out, rendering the new fluid useless.

If you have any concerns about your transmission, feel free to call Calgary’s top transmission shop—National Transmission will answer all your questions. Contact us today!

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