Best Transmission Additives: Restore Your Transmission’s Health for Smoother Performance

The best transmission additives for performance and efficiency

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If your vehicle’s transmission suddenly starts shuddering, or the changes feel harsh and uncomfortable, it could be an indication that your transmission is faulty and needs your attention. More often than not, these issues can be due to the lack of proper transmission fluid.

Fortunately, you don’t have to spend a lot of your hard earned cash replacing your vehicle’s transmission. Instead, you can go for a much simpler and affordable option and shop for the best transmission additive. To make your search easier, here’s our list of the best transmission additives on the market right now.

  • Best Overall
    Prolong Super Lubricants PSL15000
    Prolong Super Lubricants PSL15000 is a trusted additive that works for both manual and automatic transmission systems. Manufactured with a unique formula that protects against friction and heat.
    Features anti-friction metal treatment technology for treating metal surfaces. Restores responsiveness in transmission for smoother shifts. Ideal for both manual and automatic transmissions.
    Not designed to work with CVT transmission systems. Performs poorly with high-mileage SUV and trucks. Tiny bottle. Hard to use with a standard funnel.
  • Best Value
    Lucas LUC10009
    Lucas LUC10009 Transmission Fix is an affordable, 100-percent solvent-free additive that has been specially designed for slipping transmission issues. Features a polymeric film that renews bands to stop seal leaks.
    Eliminates slippage issues. Offers the perfect balance between price and performance. Comes in a 24-ounce bottle for multiple uses. Prevents foaming. No need for AFT flush or draining when using this additive.
    Not ideal for faulty or damaged transmission systems. Dismal results with old, high-mileage vehicles.
  • Honorable Mention
    Hot Shot’s Secret HSSTSE32Z
    Hot Shot’s Secret HSSTSE32Z is a high-performance transmission additive specially formulated for automatic transmission systems, including CVT transmissions. Ideal for temperature reduction and pulling deposits from coated areas.
    Ideal for both gas and diesel automatic transmission vehicles. Comes in a large 32-ounce bottle for multiple uses. Offers quick results. Reduces friction and wear.

    It is not designed for manual transmission systems. It's expensive compared to other additives in its range. 

    Might not fix extreme hard shifting problems.

Benefits of Transmission Additives

  • Stop transmission leaks. Having a transmission leak might seem like a minor issue, but its aftermath could be profound. A small transmission leak could cause your transmission system to operate poorly. Transmission fluid is corrosive, so having small leaks could damage parts close by. Therefore, investing in a good transmission additive will help minimize leaks.
  • Minimize varnish and sludge formation. After extensive use, even high-quality transmission fluids begin to wear out and thicken. This happens when dirt and other contaminants mix with the fluid forming sludge. Thick fluid moves slowly, preventing the transmission parts from moving easily and efficiently. Getting proper treatment keeps your automatic transmission fluid (ATF) viscous, helping your transmission work as it should.
  • Reduce gearbox wear and tear. When gear oil moves throughout your vehicle’s transmission, it keeps your entire system working properly. However, when transmission fluid starts getting old, thickens, or forms impurities, your transmission will be forced to work harder and won’t be as effective. The harder your transmission system works, the more wear will be put on your auto parts.
  • Reduce transmission shudder and noise. When your transmission is working harder due to poor fluid, you will feel the effect not just in increased repairs but also in the noise that it makes. You will notice clacking, whirring, and other noises from your transmission. This will significantly reduce the quality of your ride. Adding a good transmission additive will help reduce the vibration and noises that you experience driving your vehicle.
  • Prolong the life of your transmission system. Getting the right additive will help extend the life of your transmission system. Purchasing the right transmission treatment for your car will help lower its running temperature and prevent overheating. It will also help reduce the wear on parts and keep your transmission running properly.

Types of Transmission Additives

Manual Transmission Additives

Manual gears operate on a system that has two shafts with gears. These gears mesh together after user input through the gear stick and clutch. As a result, the manual transmission system creates a lot of heat, friction, and force when the two moving objects come together. Due to this, manual transmission fluid, as well as additives, need to be able to make the gears transition as smooth as possible to prevent damage to components as they shift. To achieve this, manual transmission fluids are more resistant to heat, have high viscosity, and can function under extreme pressure.

Automatic Transmission Additives

Automatic transmissions operate in a planetary system. Gears switch automatically depending on the demands of the engine. Automatic gears tend to be smaller and have more moving parts compared to a manual gearbox. Therefore, the automatic transmission fluid, as well as additives, are on a different level than manual gearbox fluid. Automatic transmission additives have low viscosity and anti-foaming properties and are resistant to heat. 

Top Brands

Prolong Super Lubricants 

Prolong Super Lubricants is an American company headquartered in California that deals in the manufacturing, sale, and global distribution of a line of high-performance automotive lubricants. Prolong’s history is the perfect example of an American success story. The company was founded back in the 1990s. The founders operated from the back of a small shop packing the products themselves. Several years later, Prolong Lubricants Inc now sells millions of high-performance lubricants all over the world. The company’s products are based on an extreme pressure lubricant additive that is used for metal lubrication, commonly known as anti-friction metal treatment (AFMT). One of its popular products is Prolong Super Lubricants PSL15000.

Lucas Oil Products Inc

Lucas Oil Products incorporated is an American company that deals in the manufacturing and distribution of automotive lubricants and additives. The company was founded back in 1989 by Forrest Lucas and his wife, Charlotte. The company manufactures engine oils, gear lubes, greases, and car care products. Lucas Oil Products Inc markets about 270 automotive formulations in 40 countries. Its original plant and headquarters are in Corona, Calif. It opened a new plant in Corydon, Ind. in 2003. One of its popular products is Lucas LUC10009.

Lubrication Specialties Inc.

Lubrication Specialties Inc. is an American company that deals in blending and distribution of lubricants and greases. It was founded back in 1997 by Chris Gabrelcik. Lubrication Specialties Inc. offers automotive products such as aftermarket additives, industrial oils, gear lubricants, engine oils, food grade lubricants, crystal greases, and other lubricants. Lubrication Specialties Inc. is popular for resolving problems for some of the largest companies in North America, including America Showa, Nucor Steel, Midwest Industries, etc. One of its popular products is Hot Shot’s Secret HSSTSE32Z

 Best Transmission Additive Pricing

  • Under $10: There are a variety of transmission additives retailing at this price. However, most of the transmission additives only offer basic functionality. Depending on the manufacturing company, transmission additives here are popular due to their basic use and affordable price. 
  • $10-$30: The best transmission additives can be found at this price range. The transmission additives have much better composition and can be used for a wide range of applications, including transmission maintenance, heat reduction, valve lubrication, transmission failure, prevention of shudders, hard shifting, and power steering maintenance. 
  • Over $30: There aren’t a lot of transmission additives over $30. Additives at this price bracket are premium products manufactured with high-quality materials for superior performance. They can be used for multiple applications, have good ratings, and offer the best results. 

Key Features

Transmission Compatibility

Start by checking your vehicle’s owner’s manual. It will show you what type of transmission fluid to use. Based on this information, you will be able to pick out the right additive. Using manual transmission additives on an automatic gearbox will have negative effects. Therefore, it’s essential that you check the product packaging for the right additive for your vehicle’s transmission system.

Transmission Fluid Type

Transmission fluids are available either in natural or synthetic forms, with synthetic transmission fluids being more popular on the market. It's important to find out what type of transmission fluid your system is using before purchasing an additive. Check the additive user instructions to find out if it is compatible with your transmission system’s fluid.

Additive Composition

The additive composition will determine the effectiveness of the product. Manufactures will use different ingredients to help boost the performance of their products. Getting a product with a good ingredient composition will offer better functionality and performance for your transmission. 

 Other Considerations

  • Quality: It's important to always stick to big brands and respected mid-sized company additives to ensure that you are getting premium products. It's tempting to buy cheaper import products or knock-offs, but they could end up costing more when you have to deal with transmission repairs.
  • Size: The bottle size often determines the number of times the product can be used. When it comes to lubricant additives, it's important to know the quantity of product that needs to be used for a single treatment. A high-capacity bottle can be used multiple times, saving money in the long run.

Best Transmission Additive Reviews & Recommendations 2019

Best Transmission Additive Overall: Prolong Super Lubricants PSL15000

Prolong Super Lubricants PSL15000

Prolong Super Lubricants PSL15000 additive is one of the best and most popular transmission additives on the market. This transmission additive can be used for both manual and automatic transmission systems. Prolong Super Lubricant works by producing molecules that interact with metal surfaces. These molecules create a protective layer that reduces heat and friction within the transmission system.

The PSL15000 promotes smooth and responsive gear changes, and it is suitable for both high- and low-mileage vehicles. A single 8-ounce bottle of Prolong Super Lubricants Transmission Additive will treat a complete transmission. 

This additive’s formula includes AFMT that chemically bonds to the surfaces of your system, providing a protective layer that helps reduce wear and tear. A drawback to this product is that it has not been designed to work with CVT transmission systems. This product doesn’t work as efficiently with high-mileage SUV and trucks. 

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Best Transmission Additive Value: Lucas LUC10009

Lucas LUC10009

Lucas Lubricants produce some of the best additives on the market that have a reputation for great results. The Lucas LUC10009 is a relatively new product on the market but still offers amazing performance and is highly recommended for transmission problems, such as slipping transmission, leakages, and hard shifting issues. It offers the perfect balance between price and performance.

The LUC10009 is a 100-percent solvent-free formula that has been designed to prevent foaming. It also helps lower the operating temperature of the fluid, stopping seal leaks. You can use this formula to revitalize old or worn-out transmission fluid—there is no need for draining. The Lucas Super Lubricants LUC10009 comes in a 24-ounce bottle. It can be used for multiple treatments.

The greatest benefit users can get is it forms a polymeric film that works by renewing worn bands that help prevent transmission slippage. This process prevents overheating, renewing fluid that becomes worn due to heavy hauling. The LUC10009 is one of the best transmission additives for slippage.

One downside is this transmission additive might not work well with a faulty or too far gone transmission system. It will also not improve performance on severely worn out transmission systems.

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Best Transmission Additive Honorable Mention: Hot Shot’s Secret HSSTSE32Z

Hot Shot’s Secret HSSTSE32Z

If you have a diesel-powered engine and you can’t find a suitable transmission additive, then Hot Shot’s Secret HSSTSE32Z is your best bet. This ATF additive is suitable for both gas and diesel automatic transmission systems. It is an ideal transmission additive if you are looking to soften up your shifts, create a smoother ride, and protect your transmission.

The HSSTSE32Z helps lower ATF temperatures, reduces friction, and eliminates rust and corrosion, improving the overall performance of your automatic transmission system. A bonus with Hot Shot’s Secret Transmission Additive is it also works with CVT transmissions. It is a high-formulation lubricant with a unique composition capable of pulling deposits from coated areas.

A big drawback to the Hot Shot’s Secret HSSTSE32Z is that it can only be used with automatic transmission vehicles. It’s also pricey compared to other transmission additives. However, you get more benefit from its 32-ounce bottle.

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  • Most additive instructions say that you can add the transmission conditioner to existing transmission fluid. However, it's recommended that you check the fluid levels first. This is to ensure you don’t overfill.
  • Before adding transmission additive, you first need to warm up your vehicle’s engine and transmission to operating temperatures. Have your car idle for 20 to 30 minutes.
  • Read the instruction label on your additive before adding it to your system. Depending on the additive, you might only require one bottle. However, two might be necessary for larger vehicles.
  • Before adding transmission additive, make sure you locate the right dipstick. In case you are uncertain of its location, check online or in your vehicle owner’s manual. Remove the dipstick and use a funnel to channel the additive into the system.
  • After adding the additive, it's recommended that you drive your vehicle for a while, shifting through all the gears.


Q: Can I add transmission additive myself?

A: Yes, you definitely can take the DIY approach. Just make sure you locate the transmission dipstick. With little preparation, this is a task you can complete in a few minutes. Make sure you carefully read both your vehicle owner’s manual and the additive user instructions.

Q: When is it ideal to use transmission additive?

A: Transmission additives are best used if you are experiencing transmission slippage, stalling, rough shifting, or seal leaks, and you want to try a cheaper option before resorting to a repair shop.

Q: Should I add a transmission additive when changing transmission fluid?

A: Unless you have been experiencing episodes of rough transmission shifting, slipping, or hesitation, it is not recommended that you add transmission treatment.

Final Thoughts

Our pick for the best transmission additive is the Prolong Super Lubricants PSL15000. It is one of the best transmission additives on the market. It reduces leaks, shudders, slippage, and sludge buildup.

For a less pricey option, consider the Lucas LUC10009.

Have experience with transmission additives? Let us know what you think in the comments below.