Updated August 23, 2019 by Brett Dvoretz

The 10 Best Transmission Additives

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Best High-End
Best Mid-Range
Best Inexpensive

This wiki has been updated 9 times since it was first published in March of 2018. Transmission health is crucial to any vehicle, but sometimes a complete flush can stir up small particles and endanger the finely-machined components. If your gearbox starts to whine, hesitate, or make clunking noises when shifting, or if you often tow heavy loads using a high-mileage drivetrain, one of these additives can protect and renew your car or truck. When users buy our independently chosen editorial picks, we may earn commissions to help fund the Wiki. Skip to the best transmission additive on Amazon.

10. Dr. Tranny's Kooler Kleen

9. Sea Foam Trans Tune

8. Liqui Moly 20040

7. Xado EX120 Revitalizant

6. Dr. Tranny Instant Shudder Fixx

5. Hot Shot's Secret Restore TSE

4. Lucas ATF Conditioner

3. Prolong Super Lubricants PSL15000

2. LubeGuard Platinum

1. Lucas LUC10009

Special Honors

Justice Brothers Automatic Transmission Conditioner Part of an extensive line of treatment products, this conditioner mitigates rough shifting in older SUVs, and it's often found at the racetrack, where it helps cut 1/4-mile times by limiting drag in the rear end. It mixes with all types of transmission fluids and grease, allowing for versatile use. justicebrothers.com

Molyslip G MTS If your car or truck has a hard time going in and out of gear, this may be your ticket to flywheel freedom. It's one of the few that's specifically intended for manual transmissions, and it reduces shifting time and effort effectively when performance is in demand. molyslip.com

Editor's Notes

August 20, 2019:

Along with the engine and brakes, a well-maintained transmission is one of the most vital aspects of keeping a vehicle in good working order. Unfortunately, it is also one of the most expensive components to fix, so rather than immediately running to the mechanic as soon as you notice a problem, consider trying one of these effective transmission additives first.

If you are experiencing slippage or hesitation during or after changing gears, we recommend you take a look at Lucas LUC10009, Prolong Super Lubricants PSL15000, and Liqui Moly 20040. All of these contain ingredients that can help make shifting smoother and restore some responsiveness. If your transmission isn't slipping, but rather just feeling very rough when shifting or shuddering periodically at slow-to-medium speeds, you'll want to look to LubeGuard Platinum and Dr. Tranny Instant Shudder Fixx.

Additives can do much more than simply make transmissions run smoother. For example, many of the formulas on our list recondition seals, however the best options for stopping minor leaks are Lucas LUC10009 and Liqui Moly 20040. If you need to rid your system of rust and minor surface damage on metal components within the transmission, Xado EX120 Revitalizant and Hot Shot's Secret Restore TSE can both help with that.

On another note, you shouldn't always wait until experiencing a problem with your transmission before reaching for an additive. Using Lucas ATF Conditioner with a good transmission fluid can go a long way towards preventing the formation of any problems in the future.

Brett Dvoretz
Last updated on August 23, 2019 by Brett Dvoretz

A wandering writer who spends as much time on the road as in front of a laptop screen, Brett can either be found hacking away furiously at the keyboard or, perhaps, enjoying a whiskey and coke on some exotic beach, sometimes both simultaneously, usually with a four-legged companion by his side. He has been a professional chef, a dog trainer, and a travel correspondent for a well-known Southeast Asian guidebook. He also holds a business degree and has spent more time than he cares to admit in boring office jobs. He has an odd obsession for playing with the latest gadgets and working on motorcycles and old Jeeps. His expertise, honed over years of experience, is in the areas of computers, electronics, travel gear, pet products, and kitchen, office and automotive equipment.

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