LAST UPDATED: October 07, 2019

The Best Transmission Additives (Review) in 2021

Best Choice Lucas Transmission Additive Lucas Transmission Additive
Premium Pick Hot Shot's Secret Transmission Restore Additive Hot Shot's Secret Transmission Restore Additive
Best Value Lubegard Transmission Shudder Fix Lubegard Transmission Shudder Fix

Car performance can be affected by a myriad of things, and the only way to maintain optimal performance besides regular maintenance is to invest in the right products for your ride. These products include motor oils and transmission fluids that keep your vehicle running like a well-oiled machine. Transmission additives also fall under the maintenance umbrella and they can make a world of difference when it comes to shifting and chatter. They help solve a number of transmission related issues without breaking the bank. The best transmission additives can be found in our guide below, so read on to find out more about their features, benefits and types.

The Best Transmission Additive

Lucas Transmission Fix is our top pick and the best additive for slipping transmission. The non-solvent formula is effective and reliable when it comes to dealing with issues related to performance. This transmission treatment gives car owners the best of both worlds in terms of quality and price with a 24-ounce bottle that will give any car the tune-up it deserves. Lucas transmission fluid decreases the operating temperature and puts an end to foaming. The formula is also solvent free and is capable of drying up most seal leaks, however, it does not work on CVT systems. In terms of prevention, this additive allows vehicle owners to carry out preventative maintenance at an affordable price.

Key Features
  • Solvent free formula
  • Reduces operating temperature
  • Does not require fluid drainage
  • Not compatible with CVT systems
  • Eliminates foaming
Specification
  • Brand LUCAS
  • Model LUC10009
  • Weight 1 pounds

There are so many automatic transmission additives on the market but Lubegard belongs in your online shopping cart for several reasons. First of all, it is an exceptional conditioner that contributes to better and smoother shifting, and   its formula acts as a natural lubricant with a high viscosity index that is capable of resisting high temperatures. This tolerance to heat prevents it from thinning out or reacting with oxygen. This feature makes it the ideal additive for old and fresh automatic transmission fluids. The formula also reduces friction, optimizes performance and lowers the operating temperature. All of the above works in favor of new seals and old ones as well. This Lubegard product is available in three different sizes and can be used with all mineral based and synthetic automatic transmission fluids.

Key Features
  • Allows heat transference in automatic transmission fluids
  • Makes automatic transmission fluids more stable
  • Anti-chatter and anti-shudder additive for clutch packs and converter clutches
  • Doubles as a seal conditioner that prolongs life of old and new seals
  • Cannot be used in CVT systems
Specification
  • Brand Lubegard
  • Model 60902
  • Weight 1.76 ounces

This Amazon’s Choice transmission conditioner from XADO is available in syringe form with two different formulas for automatic and manual gears. The formula delivers instant results when it comes to repairing and rejuvenating this integral system and does wonders for worn and scratched metal. The fast-acting conditioner can be used with all automatic fluid transmissions and does not react with or alter their chemical properties. It takes around 50 hours for the formula to complete its repairs. What is also great about this product is that it adds a protective layer to help preserve and extend the life of your vehicle’s transmission system while reducing friction and shielding it from extreme temperatures. One syringe, however, is not enough if your vehicle suffers from major transmission wear.

Key Features
  • Restores and repairs worn transmission metal
  • Reduces friction and shields system from excessive heat
  • Eliminates shudder and decreases vibration and noise
  • Universal formula compatible with CVT and semi-automatic transmission
  • Fast acting formula conditions and repairs in less than 72 hours
Specification
  • Brand XADO
  • Model XA 12031
  • Weight 0.32 ounces

The Trans Tune transmission additive from Sea Foam is another quality product made of three blended oils. The formula is not only effective in tackling transmission related problems, but it also flushes out moisture and damaging deposits found in hydraulic pumps and power steering systems. Trans Tune works with all commercial synthetic and petroleum based hydraulic fluids without altering their viscosity. It also cleans sticky valves and reduces rough shifting thanks to its petroleum-based formula. This quick action fluid conditions automatic transmission fluids and stops oil loss without softening the seals or O-rings.

Key Features
  • Petroleum based additive made of 3 blended oils
  • Flushes damaging varnish deposits and moisture from system
  • Can be used in power steering, agricultural & industrial hydraulic systems
  • Cleans and conditions without softening seals or O-rings
  • Compatible with all transmission flushing machines
Specification
  • Brand Sea Foam
  • Model TT-16
  • Weight 1 pounds

zMax transmission formula boosts performance at an incredibly cheap price. The 6-ounce bottle may be small, but it can be used for both automatic and manual gears. zMax was designed to reduce leaks and varnish as well. Fluid loss happens due to the presence of road debris and heat within the system and this is far from favorable. Varnish buildup is also a nuisance and can easily wreak havoc on the gears, which is why applying an additive like zMax is necessary. The formula can be used in modern cars without a problem but is not compatible with CVT transmissions.  

Key Features
  • Improves transmission performance
  • Can be used in manual and automatic transmissions
  • Not intended for CVT transmissions
  • Reduces friction and wear
Specification
  • Brand zMax
  • Model 51-306
  • Weight 5.6 ounces

Liquid Moly is a premium brand that offers a wide range of motor and transmission oils including a great additive for automatic transmission systems. The formula prevents oil loss and keeps the transmission components clean and free from damaging deposits. It also rejuvenates seals and reduces loud shifting noises. Poor fluid conditions and oil contamination due to oxidation can eventually lead to transmission failure. This ATF additive reenergizes old oil so it can do its job once more. It is also capable of extending the life of fresh oil. Refreshing oil performance and cleaning the small mazes within the oil galleries of the transmission play a crucial part in extending the service life of any transmission. This German creation contributes to better power steering and noise reduction and is closer to a paste than a fluid in terms of texture.   

Key Features
  • Cleans system and restores seals
  • Puts an end to oil loss
  • Provides smooth steering with less noise
Specification
  • Brand Liqui Moly
  • Model 5135
  • Weight 0.32 ounces

This Lucas Oil transmission conditioner is another premium product that works on conditioning seals and improving performance. The formula consists of a unique blend of additives that help extend the life of new and old transmissions. It also works incredibly well with all types of automatic transmission fluids both synthetic and conventional. Much like the above-mentioned additives, the Lucas conditioner was designed to reduce shudder and noise, resulting in a smooth and quiet operation. It also conditions seal and improves both oxidation and stability. Lucas conditioner can be used in new and old transmissions found in recreational vehicles and light duty trucks.

Key Features
  • Decreases noise and shudder
  • Can be used in both new and old transmissions
  • Prolongs the shelf life of transmission fluids
  • Does not impact warranty of new cars
  • Works well with both synthetic and conventional ATF fluids
Specification
  • Brand Lucas Oil
  • Model 10441
  • Weight 1.3 pounds

Car owners in search of a quick solution for transmission shudder will find it in this compact Lubegard product. The Instant Shudder Fixx is a concentrated formula that works with all synthetic and traditional automatic transmission fluids. 2 ounces may sound like a small amount, but the friction modifier formula delivers immediate results and solves shudder issues that can easily ruin your day. This additive can be used in all automatic transmission systems with a few exceptions including CVT and dual clutch transmissions. The compact tube is pricey when compared to other additives, but the instant shudder fix is highly rated and recommended so it is definitely worth the money.

Key Features
  • Concentrated formula for instant shudder elimination
  • Powerful and effective in reducing wear
  • Cannot be used in CVT-DCT and Ford Type-F transmission systems
  • Can be used with all synthetic and traditional transmission fluids
Specification
  • Brand Lubegard
  • Model 19610
  • Weight 2.08 ounces

Prolong transmission treatment was formulated to protect and repair manual and automatic transmission systems. Friction and heat can be extremely damaging in the long run and this formula was designed to reduce this damage by chemically bonding with the system’s metal components and forming a much-needed protective layer. This product comes in an 8-ounce bottle and is extremely beneficial when the system is under immense pressure. It also helps with rough manual shifting and is capable of fixing responsiveness issues in automatic transmissions. Prolong is compatible with commonly used transmission fluids and gear oils and does not affect clutches or bands.

Key Features
  • Formulated to shield system from wear and friction
  • Repairs metal surfaces on a molecular level
  • Forms a protective coat to shield system from damaging heat
  • Can be used in both manual and automatic transmissions
  • Compatible with all transmission fluids and gear oils
Specification
  • Brand Prolong Super Lubricants
  • Model PSL15000
  • Weight 12 ounces

Our final pick is a high-performance additive from Hot Shot with an effective ester formula. The formula works on lubricating and cleaning all metal components by bonding to these parts and removing sticky deposits from their surface. This additive is geared towards diesel and gas engines and its job is to eliminate stiction. It can be used in both gas and diesel automatic transmissions. However, this product was formulated for automatic transmission systems and comes in a large 32-ounce bottle with a five-year shelf life.

Key Features
  • High performance ester formula
  • Cleans, protects and restores metal components
  • Decreases heat and fiction
  • Gets rid of rust and corrosion
  • Can be used in automatic transmission systems only
Specification
  • Brand Hot Shot's Secret
  • Model HSSTSE32Z
  • Weight 2.2 pounds

Best Transmission Additives Buying Guide & FAQ

Manual transmission used to be the only transmission system found in cars but decades of innovation in the automotive field resulted in automatic gears. The evolution of this vital system was necessary especially with traffic jams becoming the norm. Transmission systems are an integral part of any vehicle and without them, driving as we know it would not be possible. It is therefore necessary to maintain them, and this process involves transmission fluids and additives. Replacing or rebuilding a damaged automatic or manual system is a headache and far from cheap. Fortunately, there are so many reputable manufacturers out there that create premium additives for all gear types. The following section showcases the main features you need to look for in additives and answers the most frequently asked questions regarding this automotive product.

Adding Transmission Additive to a Car

Features to Look for in a Transmission Additive

  • Compatibility

There are several features that you need to keep in mind when shopping for an additive for your car and compatibility is one of them. The transmission system in your vehicle will ultimately dictate the kind of additive that you need to buy. Some brands offer a two in one additive that can be used in manual and transmission systems. Consulting the owner’s manual will help vehicle owners determine the specific additive that they need to use. It goes without saying that using the wrong additive will do more harm than good so buying the right transmission additive can turn things around in a short period of time.

  • Versatility

There are two types of transmission fluids on the market: natural and synthetic. Some additives were formulated especially for synthetic types while others are only compatible with natural fluids. Knowing the fluid type beforehand will help car owners make the right choice regarding additives. Reading the instructions and ingredients on the bottle will also help you determine if the product matches your needs and expectations especially if the gearbox is giving you a hard time. Certain brands offer a universal additive that can be used in both automatic and manual gear and car owners who have both in their garage can opt for a universal fluid instead of a transmission-specific treatment.

  • Formula

Not all additives have the same formula, so car owners need to keep this in mind as well. Some formulas were designed to condition and protect while others reduce heat and friction. Others are more concentrated and deliver faster results compared to traditional additives. Some additives were designed to reduce noise while others increase fluid stability and help prevent oxidation. The best treatments are a capable of fixing all of the above mentioned issues at an affordable price.

  • Bottle size

Car owners who have more than one vehicle in need of an additive might opt for an economical gallon instead of a small bottle. One bottle is typically enough for a single treatment, but some worn transmissions may require a higher dosage. Investing in a large bottle allows you to save money on repair bills and carry out preventative care and maintenance on a regular basis. A large gallon can also come in handy during long vacations and road trips onboard recreational vehicles. It is important to note that certain quality brands such as Hot Shot’s Secret manufacture top of the shelf additives that have a five-year shelf life.

Why You Should Use Transmission Treatment

Cars both old and new are not immune from engine and transmission problems. Thankfully, there are more than just one solution to these problems no matter their size and impact on overall performance. Nowadays, additives can restore, condition and remove harmful deposits all at once. They are often called tune-up in a bottle thanks to their fast-acting formula. Adding this product to the transmission fluid can also come to the rescue in case of extreme temperatures and can solve chatter and shudder problems that can ruin any driving experience and put a damper on any road trip.  Investing in a quality transmission additive can also make a world of difference to vehicles that transport heavy cargo and cars with high mileage.

  • Prevents and reduces fluid loss

A drop-in transmission fluid can lead to rough shifting and slipping. Additives can help solve this leakage problem before it snowballs and opens the door to even bigger issues within the system. The smallest leak can cause overheating, and this alone can negatively impact performance. Fluid loss can also damage the different metal components due to the fluid’s corrosive nature. This alone can lead to costly repairs in the future especially if this loss goes unnoticed. Using a transmission additive will help reduce small leaks and put an end to corrosion since it conditions the seals.

  • Prevents impurities from forming

Transmission fluids can get contaminated over time and their consistency will change as a result. They become more sluggish and stop flowing smoothly. This change is certainly not for the better and will negatively affect the transmission system. Friction will increase due to decreased lubrication and the sluggish fluid will eventually merge with other impurities such as dirt and grime and become thicker and less effective. Varnish is one more thing to worry about since it can clog the vital parts of your transmission. This will eventually lead to failed clutches and bearings and an overall drop in performance. Fluid treatment in the form of additives will stop these impurities from forming and allow the transmission fluid to flow freely within the system.

  • Reduces wear

Components of all shapes and sizes are prone to wear and tear over time. Using additives will help slow down this process and extend the life of transmissions both old and new. Reducing wear is incredibly important especially for car owners who drive in harsh weather conditions where extreme temperatures, moisture and other elements can wreak havoc on the vehicle as a whole.

  • Reduces noise and shudder

Seasoned drivers become attuned to the familiar sounds of the engine and can easily tell if there is something unusual happening under the hood. Transmission issues become rather obvious when strange and undesirable noises become louder and harder to ignore. These noises are sometimes accompanied by vibrations and difficulty shifting. Clanking and whirring sounds are often symptoms of a strained transmission system that is low on fluid. Some car owners end up buying low quality lubricants for their car and this can exacerbate the problem as well. All the above issues can be fixed using a quality additive from brands like Lucas Oil, Sea Foam and Lubegard.

  • Prolongs transmission life

Nothing beats saving money on repairs especially if your transmission is old. This is where being proactive counts. Transmission additives allow you to carry out preventative maintenance that involves rejuvenating and protecting the system and its metal components. Using the right formula can help reduce the operating temperature of any transmission and this in turn will prevent overheating. This positive domino effect will also lead to lower fuel efficiency, smoother shifting and a long-lasting transmission. This means less money spent on fixing avoidable issues and more years added to your transmission system and its different components.

Automotive Transmission

Types of Transmission Additives

  • Automatic transmission additive

Automatic additives have a lower viscosity compared to manual additives and some formulas do more than just fix and restore. These formulas were designed to form a protective layer over the metal parts in order to shield them from extreme temperatures and corrosion. The automatic nature of these gears and their different moving parts demand a transmission additive that will clean these parts and eliminate any damaging deposits.

  • Manual transmission additive

Manual gears generate heat and friction due to their mechanism and their two-shaft system. Constant heat and friction require an effective and reliable transmission fluid that will keep all components running smoothly and efficiently. Manual transmission additives were formulated to complement the actions of the fluid and help reduce operating temperatures. They have higher heat resistance and a higher viscosity.

  • Universal additive

This additive works with both manual and automatic transmissions. This universal feature allows you to make the most out of this product especially if you own more than one vehicle. Universal additives also prevent overheating and do not change the chemical composition of transmission fluids. Moreover, they do not damage yellow metals and are capable of reducing fluid oxidation as well as foaming. Certain formulas have patented technologies that help eliminate shudder by tightening the shift cycle. They also solve issues related to valves and prolong the life of transmission fluids.

  • CVT additive

CVT additives were especially formulated to meet the needs of single speed transmissions. These additives help with shudder and slipping issues and can turn things around when it comes to performance.  Unlike automatic gears, CVT transmissions are specialized, sophisticated and expensive to repair. Their additive and lubricants are also designed with this complexity in mind. Seals and transmission fluids in need of a quick and efficient fix will benefit greatly from CVT additives that can be used in chain driven and push belt-drive applications.

Best Transmission Additives FAQ:

Q: Can I add transmission conditioner myself?

A: Yes. You can add transmission conditioners without consulting a professional by following the instructions written on the bottle. There are a few general rules that one must follow and those include warming up the engine beforehand and making sure that the amount used is enough. Some vehicles may require double the dose due to their size. It also recommended to go for a drive after adding the additive. This allows you to test out the gears. Some treatments take around two days to complete their conditioning and restoration process while others may take longer. It all depends on the formula and the ingredients used.

Q: How often should I use transmission additive fluid?

A: Transmission additive fluid must only be added if car owners experience issues such as slipping and shifting while driving. This can either be a common or a rare occurrence, so the answer depends on your car’s transmission system. Using additives, however, is not a permanent fix for severely damaged or faulty transmissions.

Our Top Pick

Lucas Oil is a well-known brand that needs no introduction and its transmission fluid additive is an excellent choice for both manual and automatic transmissions. This formula consists of a viscous mixture of friction modifiers and additives that repair and restore the system and its vital components. Cars are not immune to damage especially in the presence of harsh external factors that come and go with the seasons. Lucas transmission fix was therefore designed to solve issues like varnish buildup and rough shifting without breaking the bank. Worn transmission bands and clutch plates need a fast-acting formula that is capable of reducing friction and improving performance and Lucas can offer this in spades.  Lucas Transmission Fix is also solvent free, which makes it one of the safest additives out there. The viscous formula improves fluid pressure and allows you to extend the life of your transmission system as a whole.

Transmission fluid pouring

Conclusion

Poor performance can be a symptom of a minor problem or a serious one and being proactive when it comes to your transmission system will help you nip any minor issues in the bud. This can only be done if you invest in the best transmission additives and we have made this investment possible by showcasing the cream of the crop in terms of manual and automatic gear treatments in this guide.

Sources:

  1. Adding Transmission fluid additives – YourMechanic
  2. How to Change Your Transmission Fluid – Popular Mechanics