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

The best transmission additives for performance and efficiency.

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

Has your car’s transmission suddenly started acting up? Is it shuddering while you’re on the road, or putting you through harsh, uncomfortable changes you can feel from behind the wheel, it’s time to check out what’s happening under the hood. Problems like these could mean your transmission is in need of repairs. But it could also indicate an issue with your transmission fluid. While you might not think about your car’s transmission fluid very frequently, it’s a small part of your vehicle’s most critical system.

And in order to work smoothly and deliver great performance, you need transmission fluid for proper lubrication and function. If your transmission fluid isn’t at the right level – or if you’re using the wrong type — big problems can happen. Fortunately, you can easily maintain both your transmission and your transmission fluid with a transmission additive. Designed to protect the transmission while improving its performance, an additive can be a particularly handy tool. Wondering if you could benefit from one? We have the best transmission additives available right here, along with a guide to help you find the right fit for your vehicle.

Our Methodology

We can’t put our own hands on every item available. In these instances, we put our collective experience in journalism, research, and prior product testing to use to make our product picks. Items that are used by our own staff may get earnest endorsements as well, but we’ll never accept fees or bonuses to sell you stuff we’re not actually excited about. Affiliate revenue is always disclosed.

The Drive aggregates reviews and research from all over the internet to figure out which products are worth buying. We also put out shopping guides to help you understand how to assess the value of these things on your own. As our editorial cousins at Car Bibles say, “Knowledge is horsepower!”

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. 
  • $30 and up: 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.
  • Formulation. Every transmission additive is different, with a different formula of ingredients. While they're all meant to help your transmission`s performance, each one offers a slightly different blend. And some even have more specialized benefits. For example, some additives are more concentrated; others are meant to reduce noise. Some additives are meant to prevent oxidation.
  • Suitability. Not all transmission additives are okay for all vehicles. In fact, using the wrong additive could actually void your car`s warranty, if you don`t choose carefully. To make sure the product you choose is okay for your specific make and model, double-check whether the additive's labeling mentions if it can be used on your car.

Best Transmission Additives Reviews & Recommendations 2021


  • Most additive instructions say that you can add the transmission conditioner to the existing transmission fluid. However, it's recommended that you check the fluid levels first. This is to ensure you don’t overfill.
  • Before adding a transmission additive, you first need to warm up your vehicle’s engine and transmission to operating temperatures, so let your car idle for a few minutes beforehand.
  • 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 some 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?

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?

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?

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

Q: Do transmission additives really work?

The answer to this question depends on a few different factors. If you’re experiencing transmission issues and you choose an additive that’s specifically formulated to tackle those problems, you can see positive results. However, if you use an additive without having any issues, or if your car is newer, you may not really see any effect. In certain cases, additives can do more harm than good, so make sure to do thorough research before adding anything into your transmission fluid.

Q: What transmission additives work for slipping?

If your car’s transmission is slipping, you’ll want to find an additive that’s specifically formulated for this kind of problem. While some are formulated to clean your transmission and its components, others are made to target issues just like slipping and shuddering. Highly concentrated formulas can work fast, but make sure to double-check the label to make sure that’s the case with the additive you pick.

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.

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