Best Transmission Oil For Harley 6 Speed

Although you may not know it, changing your gearbox oil regularly is essential to ensure that your vehicle continues to function properly.

Because of the brand’s reputation, all Harley transmissions are insured with high-quality oil.

Let’s take a look at the best transmission oil for Harley 6 speed available on the market.

The right transmission oil should not be affected by the heat generated by the transmission system.

Improvements in Harley-Davidson performance can be achieved while keeping costs down by using transmission oil.

We’ve done all the legwork and put together a list of the best models available in terms of quality and performance, which you can see below.

Best Transmission Oil for Harley Davidson

The oil you use for your Harley Davidson should be chosen carefully. You may believe that all motorcycle engines are the same, but this is incorrect; rethink your position! Different engine oil products have different effects on your engine.

1. Spectro Oil R.HDPG6 Heavy Duty Platinum Full Synthetic 6spd

We’ll start with Spectro Oil R.HDGP6 transmission lubricant, which is at the top of our list. It is the ideal choice for Harley riders who are dissatisfied with their noisy 6-speed automatic gearbox.

It comes in the form of a heavy-duty transmission recipe that makes use of G4 innovation.

A small amount of oil is mixed between the gearboxes to help improve overall transmission performance, which is particularly essential for Harley-Davidson motorcycles.

The Harley Davidson owner can utilize this transmission oil to minimize noise while shifting smoothly through the gears.

2. Red Line 90226 V-Twin 20w50 PowerPack Oil

This oil package is a great relief for the most demanding motorcyclists. Not only is it cost-effective, but it also performs admirably.

In places where the weather is warmer than normal, this synthetic motor oil performs better.

The oil’s composition helps keep engine temperature to a minimum. Even at such a low temperature, the viscosity of the oil is not affected.

If you are a typical user, this oil does a better job of securing the position of V-Twin motorcycles.

3. Maxima Racing Oils Chrome 90-119016C

You have found the right place if you are looking for synthetic transmission oil. Everything with a dual-chamber system is compatible with this system.

In addition, you will get better performance, which is essential to avoid thermal breakdown and oil deposits.

This oil has the safest blend available to keep your bike’s gearbox cool, preventing it from overheating.

It is intended for use in Harley-Davidson models that have v-twin engines. This is something that has been taken into consideration when developing this synthetic oil.

This transmission oil is the best choice for maintaining gearbox performance in any level of humidity.

In this way, the transmission can be maintained for a longer period of time.

4. ZF LifeGuard Transmission Fluid

When it comes to transmission oil, chances are you’ve heard of or seen one of ZF’s products at some point in your life.

ZF is a well-known producer of complex gearboxes for cars from different manufacturers, such as VW, Audi, Mercedes-Benz, and BMW.

ZF manufactures transmissions for a wide range of vehicles. In addition to gears, they also manufacture transmission fluids for use with them.

Their goal is to increase the efficiency of your 6-speed gearbox and extend the life of the transmission.

The process is lengthy and, for some, a bit complicated. This is because it needs at least two washes at certain temperatures.

Overall, this is a high-quality mixture that will help increase the efficiency of your Harley 6-speed transmission.

5. RAVENOL J1D2113 ATF (Automatic Transmission Fluid)

This particular product comes from the well-known RAVENOL brand. It has been developed to be compatible with 6-speed and 8-speed gearboxes.

When deciding whether to use transmission oil for Harley-Davidson or for other types of cars, this is the oil that you should choose from the list.

It says it can be used in a number of cars, including Audi, Acura, BMW, Land Rover, and Honda, among others.

Transmission wear is greatly reduced by it. The fluid’s high viscosity index helps prevent overheating while in use.

All excellent transmission oils, including this one, are capable of performing in a range of climatic conditions.

6. Bel-Ray Big Twin Transmission Oil

A well-known manufacturer of high-performance products, this product is intended specifically for V-Twin engines, such as those found in Harley Davidson motorcycles, and comes with a lifetime warranty.

This product has sophisticated ingredients and excellent chemistry, which minimize friction while protecting sensitive components from stress.

This oil is designed for end drivers and those using Big Twin transmissions with hypoid gear oil in the following applications: standard and limited differential in sliding and driveshaft transmissions; standard differential in sliding and driveshaft transmissions.

To prevent shear breakage of the gears, there is usually a higher viscosity. There is often greater shear stability because the viscosity resists shear-induced breakage of the gears.

7. Red Line (42804) V-Twin Transmission Car Gear Oil

This transmission oil is intended for use in a wide range of motorcycle models.

However, it will provide the greatest effects when used in a four-stroke motorcycle or off-road vehicle, and Harley-Davidson will provide the best results.

This oil shifts quickly and smoothly, making it ideal for racing. This oil has viscosity characteristics that allow it to act as a protective coating over large teeth.

This function ensures that the oil has sufficient thickness. Even if the oil has not been changed for a long time, this oil continues to provide reliable service.

Prevention of overheating is an advantage of using this oil.

8. Mobil (112812-4PK) Delvac Synthetic Transmission Fluid

Mobil’s Delvac synthetic transmission oil is another excellent upgrade for your Harley’s 6-speed gearbox. When it comes to quality and reliability, Mobil is one of the few brands that can stand up to the competition.

For example, Delvac transmission oil is a great example of this.

The oil has been specially formulated to improve the efficiency of your transmission by a considerable margin.

It includes synthetic base oils and additives that contribute to the development of gear and shifting performance under various conditions. In addition, the oil helps prevent wear, thus prolonging the life of synchronizers and gear bearings.

In conclusion, we think this fluid is your best choice if you are looking for a solution that will improve the efficiency of your Harley 6-speed while protecting the components. Most importantly, it can be installed in almost any vehicle.

What Is 6 Speed Transmission Oil?

If you ride one of the new Harley-Davidson motorcycles, you’ve probably discovered that the extra gear is useful in several ways.

The most significant benefit of using a 6-speed transmission is that it helps overcome the problems of sluggish acceleration that are pervasive with 5-speed and lower gears.

In other words, you can drive for hours on local highways without fear of overworking the engine. However, this is rarely the case with Harley Davidson motorcycles.

This is because, unlike water-cooled motorcycles, Harleys rely on air cooling and therefore heat up easily when traveling at higher speeds. Fortunately, transmission exists to solve this problem.

Transmission oil is a lubricant used to keep the components of a 6-speed transmission cool even if the motorcycle is traveling at high speed for an extended period of time.

When the proper oil is used, the motorcycle can operate smoothly even at high speeds or under heavy loads, with a minimum of vibration and noise.

This is because the oil serves as a coolant and is therefore not affected by high temperatures during long journeys.

Things to Consider Buying Transmission Oil For Harley 6 Speed:

If you don’t know what to look for when it comes to choosing the best transmission oil for Harley 6 speed, it can be a difficult task.

When it comes to buying oil for your Harley, you may be debating whether or not to do so. If so, you’re not alone.

Consider all the variables that go into the final choice of whether or not to buy transmission oil before making a final decision.

Viscosity and Oil Grade

The flow resistance of oil is used to determine its viscosity (or thickening). When determining the viscosity of an oil, two numbers must be taken into account.

The first number has the letter “W” at the end, which stands for Winter. Specifically, this measurement relates to how the oil flows when it is cold, for example, when an engine is first started.

At higher typical operating temperatures, the second number is determined by the way the oil flows through the engine.

The lower the number, the better the oil flow. As a result, at initial temperatures, a 5W-30 will flow more readily than a 10W-30, and at typical engine operating temperatures, a 10W-30 will flow more readily than a 10W-40.

This is critical, as engine oils tend to thicken as they cool and lighten as they warm.

Light, low-viscosity oils flow more easily and effectively to protect engine components when temperatures are below freezing.

High viscosity oils, which are thick and viscous, tend to preserve surface tension better, which helps protect engines when operating at high temperatures.


The use of additives is another important element to improve the overall performance of the motorcycle. It is one of the most widely used and advantageous variables available.

It is true that several motorcycle transmission oils include a variety of chemicals to help them perform better. Specifically, it has the ability to remove particulates as well as vinegar.

The cost

The cost of transmission oil should not be forgotten. The cost of transmission oil varies depending on the quality and brand.

Most of the time, one chooses to buy a low-cost item.

However, that is not at all appropriate. There is a lot of high-quality transmission oil out there, but it is expensive.

Expensive oil will provide you with the best support. So don’t be afraid to pay money to keep your Harley’s engine in good condition.


Buying the wrong motorcycle oil can lead to a number of complications. Make sure you don’t choose the wrong type. It is essential to choose the right oil.

Buying the wrong oil wastes money and effort. If you use the wrong transmission oil, you run the risk of damaging your motorcycle’s engine.


How many quarts would a Harley-Davidson transmission take?

The amount of fluid required is determined by the fluid you choose. In the motor, chaincase, and tranny, several chemicals may be used.

As a result, for the Harley, a quart of fluid should suffice.

When and how often do I change the transmission oil in my Harley-Davidson?

An oil change can be performed every 5,000 miles, according to the owner’s manual.

At 10,000 miles, you can have your first oil changing, and at 20,000 miles, you can have your transmission oil changed.

An oil changing for the transmission can be done once a year. It is simpler to remove the wreckage and ammonia from the oil while it is wet.

The frequency is determined by how hard you are riding and how far you have been.

What kind of transmission fuel can be used in a Harley-Davidson?

Your transmission oil will be certified by Harley Davidson. The motorcycle’s warranty would not be void in this manner.

Temperatures, pressure, and load can all be extremes for your transmission of gasoline.

Is synthetic oil preferable to conventional oil?

You may need fewer oil changes if you use synthetic oil and you would ride your motorcycle for hundreds of miles before requiring one.

Synthetic oil often decreases transmission noise by lubricating the gear teeth and avoiding the friction that causes the noise.

Furthermore, synthetic oil performs best in harsh weather. It also reduces overheating and assures that the system runs smoothly.

Are there times that synthetic oil should not be used?

You will use your synthetic oil wherever you can, whether your motor is new or old. Regardless of the engine’s age, the oil promises ideal performance.

Synthetic crude, on the other hand, is extremely slick. To run effectively, several components of a new engine must be mated. As a result, synthetic oils may make mating more challenging.

Is synthetic oil a multipurpose product?

Some vendors may claim that a single oil product would suffice for all of your lubrication requirements.

This is not the case, nonetheless. Synthetic oil for your facilities, synthetic oil for your clutch, synthetic oil for your chain, and synthetic oil for your engine are all recommended for optimal performance.

Synthetic oil for your equipment helps to safeguard your machinery and bearings from wear while still allowing for easy gear shifts.

When moving gears, lubricating the gear teeth decreases noise enormously.

Synthetic engine oil keeps your vehicle healthy and tidy at all times. As the oil circulates through the engine, it meets dirt and debris from different components, providing the required lubrication.

The oil absorbs dirt and inhibits it from accumulating, which would impair its performance.

Is it true that using synthetic oil voids my warranty?

The majority of synthetic oils do not invalidate your manufacturer’s warranty.

For the warranty to be legitimate, it must satisfy or surpass the specifications of many motorcycle brands.

Which synthetic oil is the safest to use?

You should choose from a variety of synthetic oils on the market.

According to our findings, the top three varieties of synthetic oil are included in this article.

Red Line 42804 V-Twin transmission oil is one of them, and it’s particularly good for sports bikes and four-stroke motocross.

We also have Spectro R HDPG6 heavy-duty synthetic diesel, which is compatible with six-speed transmissions.

Six-speed transmissions are known for their high efficiency. It will, therefore, be very loud.

As a result, the synthetic oil allows shifting through the gears a breeze, removes disturbances, and decreases the 5th gear’s whine.

The Amsoil MYTQT-EA V-Twin transmission fluid is the final choice. The synthetic oil prevents wear and tear on the gear, chain, and bearings. It also helps with acoustic removal and smooth shifts.

Liam Dare

As CEO of, my passion for the automotive world motivates me to build online businesses that provide information and entertainment to users. I am proud to contribute in a positive way to the automotive community.