What Oil Goes in a Harley Transmission


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What Oil Goes In A Harley Transmission

Do you have a Harley-Davidson bike, but you aren’t sure what type of oil goes in the transmission of your Harley-Davidson bike? If yes, then you are definitely in the right place.

What oil goes in a Harley transmission is a question that almost Harley-Davidson biker has at some point. It is recommended that you need to use 20W-50 Synthetic Motorcycle oil in the engine, transmission, and primary chain case on most Harley-Davidson bikes. Using this oil will give you a wide range of benefits such as convenience, simplicity, great all-around performance, and more. Remember that using the wrong type of oil could harm your bike and leave it in need of servicing.

In this article, you will get to know all about transmission oil in Harley-Davidson bikes, what oil goes in a Harley transmission, differences between different types of oil, factors to consider when buying oil for Primary transmission, and more. Continue reading to get all the answers that you are looking for.

Oil for Harley-Davidson Transmission

Oils play a significant role in the inner workings of a Harley-Davidson bike. Not only will the right type of oil ensure proper gear control and lubrication, but it will also help keep the components in their best shape and ensure a long life for your bike. This is why it is important to get the best type of oil for your Harley-Davidson bike’s transmission.

But unfortunately, not everyone knows which oil and how much transmission oil goes into a Harley-Davidson bike. As there are several options available in the market, it can be quite hard to choose the very best one. Luckily, this is the right place for you to be if you want to learn about transmission oil. 

Some V-twin bikes such as Indian and Victory motorcycles use a shared sump, which means that they use the same lubricant in the transmission, engine, and primary chainsaw. Meanwhile, most Harley-Davidson bikes use a separate sump for every lubricant. This presents Harley-Davidson bikers with a choice – either use the same lubricant in all three areas of their bike, or use a separate lubricant formulated and labeled for different areas.

What Oil Goes in a Harley Transmission?

If you are a Harley-Davidson biker, you will want to know which type of oil goes into the transmission. Here you will get guidance for deciding what is the right option for you.

It is recommended 20W-50 Synthetic V-Twin Motorcycle Oil is the best oil option for not just transmission but also the engine and primary chaincase in most Harley-Davidson bikes. It offers a wide variety of features such as –

  • Convenience – The riders can buy and install one lubricant, which reduces cost and results in fewer number of half-used oil bottles lying around the garage 
  • Simplicity – Remembering to purchase one lubricant will be much easier than remembering to buy three different oil bottles for different components 
  • Amazing all-around performance – You can get great all-around performance in all three components of your Harley 

The 20W-50 Synthetic V-Twin Motorcycle Oil is formulated to be an impressive all-around lubricant. It is capable of delivering exceptional engine protection because of its proven ability to fight wear, maintain cleanliness, reduce heat, and prevent any corrosion during storage.

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Synthetic V-Twin Motorcycle Oil will also boast a shear-stable formulation. It will resist viscosity loss despite the intense pressure and the churning action of high-RPM transmission gears, which allows it to deliver reliable transmission protection. 

This type of oil also meets the JASO MA/MA2 standards, while it is wet-clutch compatible for amazing performance in the primary chain case. Its frictional properties can be dialed-in for allowing the clutch plates to engage and disengage without loading or slipping for smooth shifts.

Can One Motorcycle Oil Be Used for All Three Areas of the Bike?

Despite the numerous benefits and positives, some bikers also question the practice of using one lubricant in all three areas of their motorcycles. They have a tough time accepting that the same oil can also be used for transmission, engine, and primary chain case. If you don’t want to use the same oil in all three areas, then you can use options like Synthetic V-Twin Transmission Fluid and Synthetic V-Twin Primary Fluid.

Is There Any Difference Between Transmission Fluid, Motorcycle Oil, and Primary Oil?

Essentially, most transmission fluid and primary fluid options are formulated for protecting just one area of your bike, instead of all three. This allows the brands to over-engineer each lubricant for precise application.

Synthetic V-Twin Transmission Fluid comes with a higher viscosity compared to the 20W-50 Synthetic V-Twin Motorcycle Oil. A thicker or higher-viscosity lubricant will offer more advantages in helping quiet down transmission gears and enabling smooth shifts. The lubricant develops a thick fluid film on gears, which will offer an extra cushion to help diminish loud “thunks” and gear noise.

Likewise, Synthetic V-Twin Primary Fluid comes over-engineered for protecting primary chaincase components. The viscosity will be like an SAE 50 motor oil. Formulating this type of oil as a straight-weight lubricant will naturally offer better shear stability over multi-viscosity lubricants. This will help make the fluid thicker, which will help it cling to the compensator without getting “flung off” as easily, for maximum protection.

In Harley-Davidson bikes, the compensator acts as a shock absorber for preventing engine vibration from affecting the transmission. The compensator wear can often lead to a knocking or ticking noise. Synthetic V-Twin Primary Fluid will cling well to the chain for amazing wear protection. Meanwhile, the wet-clutch-compatible formulation will also meet JASO MA/MA2 requirements.

Which Oil Option is Best for Harley-Davidson Bikers?

Now, you might be wondering which is the best option for Harley-Davidson bikers. Well, it will depend on what you value the most.

Different Harley Oil

For bikers who are looking for the simplicity and convenience of using one lubricant for all three areas, then you should go for 20W-50 Synthetic V-Twin Motorcycle Oil in all three areas as it would be the best choice.

Meanwhile, for bikers who want lubricants dialed in for specific areas of their bikes and don’t mind purchasing a few extra bottles, then you should use the specific oil option for the specific area.

Things to Consider Before Purchasing the Transmission Oil

If you are going to purchase transmission oil for your Harley-Davidson bike, then there are a few things that you need to consider. Here are the things that you should think about before purchasing transmission oil – 

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1. Viscosity

Not just for Harley-Davidson bikes but for any motorcycles, cars, trucks, or other vehicles, the viscosity will be an important factor. You need to know about your Harley-Davidson motorcycle’s viscosity level perfectly. You will get all the information that you might want in the owner’s manual. However, there are a few basics that every Harley-Davidson bike owner must know about, such as viscosity.

Viscosity essentially refers to the speed of the flow of the oil. Essentially, the higher the viscosity, the faster the oil will flow. It will be vice versa for lower viscosity levels. This is why you should know your motorcycle and check the viscosity level to decide which type of oil to go for.

2. Type

The oil type is another thing that you should consider. You need to know what type of oil will be suitable for your Harley-Davidson bike. Basically, there are three types of oil –

  • Mineral-based oils – There have been questions regarding the stability of these oils but they might not always be the best for your bike 
  • Semi-synthetic – This type of oil will cost slightly less comparatively. They will be a mixed version of crude oil and synthetic components.
  • Full-synthetic – This is the best oil option for your bike. They are easily compatible with Harley-Davidson motorcycles. In fact, they are the most common fluid type for Harley-Davidson bikes.

Most bikers prefer using full-synthetic oils, and it is recommended that you should too. It could be slightly costly, but it will definitely get the job done. However, you need to check the owner’s manual or directly contact the manufacturer to be sure of the type of oil you need.

Considering this before buying the transmission oil, as it’ll be of great help when looking for the best oil option for Harley transmission. 

3. Quality

You must always check the quality of the oil before using it on your bike.

You have likely spent thousands of dollars on your Harley-Davidson bike, so why should you compromise on the Harley-Davidson transmission oil quality?

You need to identify the best oil options that offer the most benefits to your bike. Even if you’re having trouble with the budget, you will definitely find a great oil option under your budget too. So, you shouldn’t go for any type of oil and use only the best ones.

4. Longevity

Longevity is another thing that many people do not consider before they make the final purchase. Longevity of the product should be noticed and considered in every circumstance. You can ride your bike in almost every type of weather, so the longevity of the oil must be noted.

5. Price

Many bikers give suggestions about their own favorite oil options but not everyone has the same type of budget. So, you need to choose the most budget-friendly option that is available for your bike. However, it is recommended that you should not always go for the cheapest one. Spend a bit of time and you must get the best option possible.

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6. Additives and detergents

You need to check the formula of the transmission oil and identify the additives and detergents. Try to find how much protection the additives can provide. How clean will the oil make the engine?

You will require protection from wear and tear, high temperature, deposits, and more. The oil must contain different additives and detergents for that. Considering these factors is a must when purchasing a new transmission oil.

7. Reviews and recommendations

Another thing that you need to consider is the reviews and recommendations of reputed websites and bikers.

Many people would have used that brand of oil before you, so they’ll have the experience of using that oil. You need to try and check the reviews or research about it on your own.

Further, you have to check the average rating on the reviews. You should also check why the bikers are recommending it, and then make the purchase accordingly. 


Are primary fluid and transmission fluid the same?

No, they aren’t the same things. There are definitely a few differences between Harley-Davidson Transmission Fluid and Primary Fluid. Most of the time, transmission fluids will have higher viscosity. Viscosity is essentially the speed at which oil flows.

Transmission fluids will help in reducing transmission gear noise while also helping in enabling easy shifting. On the other hand, most Primary Fluid options will be a lot thicker. They focus on offering much better stability and great performance.

How often should you be changing the oil on your Harley-Davidson bike?

How often should you change the oil on your Harley-Davidson bike will depend on how much you ride and the type of oil you are using. If you are using semi-synthetic oil on your Harley-Davidson bike, then you need to change the oil after riding 5,000 to 8,000 miles. Meanwhile, if you are using synthetic oil, you need to change the oil every 7,000 to 10,000 miles.

Can I use engine oil in my bike’s transmission?

No, it isn’t recommended that you should use oil on your bike’s transmission. If you are using engine oil in the transmission, then there might be poor lubrication.

Moreover, if you are using it in the wrong area, you might face overheating issues on your bike too. In fact, some people could even face entire transmission failures due to it. This is why it is recommended that you shouldn’t use engine oil in your bike’s transmission.

What happens if you use gear oil in transmission?

This will depend on the transmission that you are using. While most transmissions use gear oils, some of them do not. If the transmission uses gear oil, then you’ve got nothing to worry about. You need to use the best possible gear oil in perfect quantity.

If the transmission is not suitable to gear oil, then you could be making a major mistake. It may work for a while, but it will eventually damage the engine in due time.

How much oil can your Harley-Davidson bike hold?

The transmission fluid capacity of a Harley-Davidson bike is around 0.7 liters, or around 24 ounces.

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White Star Rides is your go-to Harley-Davidson expert. We live and breathe these bikes. Our team has years of experience in fixing, riding, and loving Harleys. We know every part of these bikes and love sharing what we know with you. Whether it's about fixing a problem or just enjoying the ride, we're here to help. Trust us to make your Harley journey better and easier.

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