6 Best Transmission Additive of 2022 | Ultimate Buyer’s Guide | Reviews

If you neglect your car’s transmission, it can definitely cost you.

In fact, even on more reliable vehicles, when the transmission starts to go, you can sometimes expect to spend more than the car is worth repairing it. For this reason, over the life of the vehicle, it’s a good idea to use a transmission additive; these additives can extend the functionality of the transmission so that you won’t experience slipping or hard shifting, even as your car starts to age.

In this guide, we’re going to show you the six best transmission additives on the market so that you will know precisely what to look for to extend the life of your transmission. In addition to this, we’ll also provide you with a buyer’s guide that will help educate you about this type of product.


Transmission Buyer’s Guide

How Does an Additive Extend the Life of Your Transmission?

Your transmission needs fluid so that the gears and bearings are protected from wear and tear. Remember, the transmission is always working hard and allows you to shift gears fluidly without strain, and a functional additive facilitates this process by effectively renewing worn transmission fluid and restoring its viscosity and heat resistance. Additionally, one of these products can provide improvements in anti-shudder durability, which will increase transmission performance overall.

As a result, you’ll have to change the fluid less often, and you’ll effectively experience less mechanical and component breakdown inside of your transmission. Typically, to get these same results, you’d need a full fluid flush replacement of the transmission fluid, and this can be a bit on the costly side. Instead of this, you can just add the fluid, and most of these cost very little comparatively, so there are a lot of advantages to just adding one of these products.

Adding the Additives to Your Transmission

One of the best features of these products is how easy they are to apply to a transmission. Similar to adding transmission fluid, you just pour in the additives after you remove the dipstick. Usually, this is best done by using a funnel, but for most brands, the process is very straightforward.

On the other hand, there are products on the market that will require that the transmission be fully drained. Unfortunately, these additives can be a bit less cost-effective, but they may also provide a slightly longer-lasting performance boost for your transmission. With that stated, the pour-in products are much easier for most people.



Best Transmission Additive Reviews


1) zMax 51-306 Transmission Formula

The first product in our guide provides a good performance boost for both manual and automatic transmissions. While continuously variable transmissions, or CVT transmissions, aren’t compatible with this additive, zMax’s 51-306 still has the right level of compatibility with most modern cars. The product is designed to reduce the occurrence of leaks, and it’s also capable of reducing the appearance of varnish, which is a result of worn transmission fluid adhering to the walls of your transmission and gumming up the works.

Overall, this is a very useful product, and it’s also one of the cheapest transmission additives that you can find on the market. It’s also designed for ease; you can simply pour it directly into your transmission, and it’ll start to work at improving overall performance reasonably quickly. Once it’s worked its way into your transmission system, it effectively revitalizes your transmission fluid, which will keep wear and tear damage from forming on the components. zMax provides a six-ounce sizing for this transmission additive, which means it really takes a very small amount of time to pour it into the car.


  • This is a very inexpensive option, and it can boost the lifespan of your transmission.
  • It comes in an easy-to-pour bottle.
  • This is a relatively fast-acting product.


  • This product isn’t designed for continuously variable transmissions.
  • Its effects don’t last for very long, so you may have to buy more.



2) BG AT5 Plus

Our second product stands out because of the fact that it’s designed not only to enhance the properties of newer transmission fluid, but also to ensure that your older fluid is rejuvenated. This means that it will not only help reduce the varnish that appears on the transmission’s components, but older fluid will even start to better lubricate these same structures. In addition to this, the oxidation stability of this fluid is much improved, which means that you’ll be able to go longer between transmission fluid changes.

This BG AT5 Plus additive also prevents foaming, which is very useful as transmission fluid has a tendency to foam when under pressure. Anything that actively prevents this will significantly improve the performance of the transmission because more of the fluid will be able to circulate thus ensuring that the gears and bearings are well-lubricated.

Over time, the seals in your transmission will start to stiffen due to age and exposure to the fluids within the component. As a result, fluids can begin to leak out as the seals become less effective due to the stiffening. This additive actually helps keep the seals on your transmission pliable, so over time, you’ll experience minimal leaking.


  • This product actively prevents transmission leaks.
  • ATC Plus actively prevents the formation of foam.
  • Fluid oxidation stability is greatly improved.


  • It doesn’t work on dual-clutch transmissions.



3) 3422 Molyslip G Manual Transmission Supplement

This product, which is manufactured by Molyslip Inc, is an additive that works somewhat differently to some of the other products that we’ve featured in this guide. The first difference of note is the functionality. Instead of rejuvenating the transmission fluid inside your car, this product actually adheres to the gear surfaces inside of your transmission, dramatically reducing the friction during standard transmission operation. As a result, adverse transmission effects like lacquering and foaming won’t be able to cause issues for your car at all.

Effectively, this supplement will help keep your transmission fluid vital, as the number one degrader of this essential transmission substance is the heat and friction being produced by your transmission’s everyday functions. This product also blends with the transmission fluid, which adds thousands of miles to its lifespan. It’s also important to note that this product is specially designed for manual transmissions, so if you’re driving an automatic, there are better products on the market for your type of car.

When you’re ready to use it in your transmission, Molyslip has made the process reasonably easy. It is supplied with an adapter tube so that you can pour the supplement directly into your transmission.


  • This product plates directly onto your transmission components so that a protective layer is formed.
  • It adds vitality to existing transmission fluid.
  • Molyslip packed in a tube to assist in pouring the fluid into the transmission.


  • It is only for manual transmissions.



4) ATP Automotive AT-217 Titanium Protectant & Modifier Synthetic Transmission Additive

This product serves as a reasonably premium solution for maintaining the lifespan of your transmission, and if you tend to drive your vehicle a lot, this AT-217 product will definitely stand out. This is due to the fact that it’s specifically formulated to work well in high friction environments, so it’ll last when your transmission needs to change gears often. The product uses a unique formulation that’s designed to prevent fluid that uses a Dexron and Mercon blend from forming both sludge and foam, so the transmission functions are well protected.

Also, the unique formulation will keep the transmission fluid from oxidizing, which is another useful feature for those who are looking to increase its lifespan. If you are a fan of expensive European cars, then AT-217 can really work well thanks to its unique formulation and oxidation-preventing features. It is even designed to help prevent overheating in the transmission, which can cause lacquering.

This transmission additive comes in a 10-ounce sizing, which is enough to work on a single car. Additionally, it also comes with a bottle cover that can be used as a funnel for application.


  • This product incorporates synthetics.
  • This greatly reduces friction and oxidation.
  • It virtually eliminates any instances of foaming and sludge.


  • The extra lubrication features that this packs in are primarily designed for certain European cars.



5) Power up Nnl-690 Engine Oil Additive

The next product in our guide is actually designed to work with both your transmission and your engine, to significantly reduce the operating temperature of this vital component so that there’s less equipment stress overall. As a result, parts will experience less friction-related stress, and your whole system will benefit from the extra lubrication that this product provides.

Additionally, the formulation is designed to prevent the formation of varnish on both your engine and transmission, which can ensure that components in both systems don’t slow down due to this gummy formation. Power Up Lubrication has also designed this to help keep seals more pliable and actually enhancing the seal that does exist, thus ensuring fewer leaks in the transmission, which will keep fluid levels high.

This additive is designed to prevent cavitations and add anti-shudder durability to your transmission. It is also important to note that when you enhance the friction resistance of a transmission, extra fuel economy is provided, and since this product tends to protect for longer periods, it can really help save you some cash on gas.


  • This provides a protective layer of film on your transmission’s metal components.
  • The protective layer can increase component lifespans up to 2.5 times.
  • This works to improve the functionality of both the engine and the transmission.


  • It can be a bit more expensive than other products on the market.



6) Cerma Engine Treatment

Our final product is another additive that can enhance both the engine and the transmission, and it uses a proprietary STM-3 lubrication tech to enhance and thoroughly coat the metal components of both systems. To apply this fluid to your vehicle, you simply add it during an oil change, and you’ll see results almost immediately. The STM-3 lubricant is specifically designed to reduce engine vibration, lacquering, and noise.

During the lifetime of a car, various carbon deposits can form as a result of high temperatures and friction. This product has the ability to break up these carbon deposits so that you can experience a heightened level of performance in the car. This component uses SiC technology that helps the product form a micro-ceramic seal on various car components. This seal lowers the friction caused by the metal components, which will then allow the transmission or engine to run at lower temperatures.


  • You can experience heightened horsepower and fuel economy with this product.
  • It’s relatively easy to use; just add it during an oil change.
  • It actively coats the metal components of your car to protect from friction.
  • It can aid in reducing the noise level of your car.
  • The company offers a money back, no-questions-asked guarantee.


  • You have to add this during an oil change – you can’t just add it to your transmission.



Final Thoughts

Our cars are designed to make it easier for us to get from point A to point B, and if you’re looking to extend the life of your vehicle, you’ll need to find the best transmission additives for the job.

Each of the products that we have covered in this guide will provide you with enhanced performance, reduced friction, and an extended transmission lifespan.

If you’re not 100 percent sure which product to purchase, take another look at our reviews and check out our buyer’s guide, which will provide you with the answers you need in order to make an informed purchase.