Picking best oil for harley davidson is a big deal. Owners talk about it. So do mechanics. This is for a good reason. The big V-twin engine is air-cooled. It has special needs. It is not like a car engine. It is not like other bike engines. Oil in a Harley does more than one job. It keeps parts moving. It also cools the engine. It takes away a lot of heat. This is a hard job for oil. The right oil helps the engine run well. It helps the engine last a long time.
Most Harleys have a “three-hole” system. This makes it more complex. Many bikes use one oil for all parts. Harleys have three separate places for oil. One is for the engine. One is for the primary case and clutch. One is for the transmission gears. This leads to a big debate. Should you use one oil for all three holes? Or should you use a special oil for each hole? Each part has a different need. The engine gets very hot. The primary case needs the clutch to work right. The transmission needs a strong oil for the gears.
So, there is no single “best” oil. You need a good oil plan. Your plan should use facts. Look at what Harley says to use. Look at other oils you can buy. The best choice depends on many things. It depends on your engine. It depends on how you ride. It depends on the weather. It depends on what you want. Do you want easy changes? Do you want to save money? Do you want the best performance? This report gives you the facts. It will help you make a good choice.
What Harley Says to Use
First, let’s look at what Harley says. This is the base line. The company’s rules are the minimum you should use. They are important for your warranty. Harley tests its oils a lot. They test for millions of miles. They test in labs. They test in the real world. They test in very hot and cold places. Harley has a clear plan for its oils. They want oils that work well and are safe for their bikes.
1. A Look at H-D Oils
Harley sells a few types of oil. Each oil is for a certain use. Another company makes the oil for Harley. That company is Citgo. But the oil is made to Harley’s own rules. Harley is selling a promise. They promise the oil will work in their engines. This makes owners feel safe. The oil costs more because of all the testing.
Genuine H-D 360 Motorcycle Oil
This is Harley’s stock oil. It is a mineral oil. Many new bikes use this oil.
H-D 360 has special additives. This mix helps your engine last. It keeps the parts cool and clean. It also stops sludge and rust.
It comes in a few weights. The 20W-50 is used most. This oil keeps your warranty safe. It is a good oil if you change it on time. It costs less than other oils.
But it is made from crude oil. Its parts are not all the same size. This means it can break down in high heat. A Harley engine runs very hot. Man-made oil is better for high heat.
You can buy oil change kits with H-D 360 oil. These kits are easy to use.
Screamin’ Eagle SYN3 Full Synthetic Motorcycle Lubricant
SYN3 is Harley’s best oil. It is a full synthetic oil. It is good for high-power engines. It is good for tough riding. It is made to work better in all temperatures. SYN3 protects parts from wear when it is hot. It also keeps the engine clean. It keeps the primary and transmission clean too.
SYN3 is a “3-in-1” oil. This makes it easy to use. You can use it in all three spots. You can use it in the engine. You can use it in the primary. You can use it in the transmission.
This makes oil changes simple. You only need to buy one type of oil. SYN3 is a great oil. But this does not mean you change your oil less. You still need to follow the oil change guide.
Fuel can get into the oil. This happens when you start the bike. So, you must change the oil often. You can buy oil change kits with SYN3 oil. Kits are sold for many types of bikes.
The New SYN3 15W-50 Oil
Harley made a new SYN3 oil. It is a 15W-50 oil. This oil is made to be stronger. It works very well in high heat. It is also better for cold starts. It is better than a 20W oil in the cold. The company says it flows like a 15W oil when cold. It protects like a 50 oil when hot.
This new oil is important. It is safe for all bikes that use 20W-50 oil. It is the new top oil from Harley. This also shows that 20W-50 can be made better. It can be better for cold starts. Other oil companies have said this for years. Their 10W and 15W oils are good for cold starts. Now Harley has a 15W-50 oil. This shows they agree.
2. What the Oil Numbers Mean
You must pick the right oil thickness. This is called viscosity. It depends on the outside temperature. Oil that is too thick is bad in the cold. It can cause wear when you start the engine. Oil that is too thin is bad in the heat. It may not protect the engine parts. Harley gives clear rules for this.
The main oil is SAE 20W-50. It is for most weather. Use it when it is above 40°F (4°C). This oil is strong. It protects the engine from heat. The “20W” is for its thickness in winter. The “50” is for its thickness when hot.
Harley suggests other oils for extreme weather:
- SAE 10W-40: Use this in cold weather. Use it when it is below 40°F (4°C). It is great for cold starts. It flows easily to engine parts.
- SAE 50: This is a single-grade oil. Use it when it is always above 60°F (16°C).
- SAE 60: This is a very thick oil. Use it in very hot places. Use it only when it is above 80°F (27°C).
SAE 50 and SAE 60 oils are good for heat. But they are bad for cold starts. Do not use them if the temperature changes a lot. SAE 20W-50 is the best choice for most riders.
| Oil Type / Viscosity | Lowest Ambient Temperature | Cold Start Performance (Below 50°F / 10°C) | |
| H-D Multi-grade SAE 10W-40 | Below 40°F (4°C) | Excellent | |
| H-D Multi-grade SAE 20W-50 | Above 40°F (4°C) | Good | |
| H-D Regular Heavy SAE 50 | Above 60°F (16°C) | Poor | |
| H-D Extra Heavy SAE 60 | Above 80°F (27°C) | Poor | |
| Table 1: Harley-Davidson oil rules for outside temperature. Data from H-D. |
3. What to Do in an Emergency
Harley has a plan for emergencies. What if you cannot find Harley oil? The company manual says you can use diesel engine oil. Look for oils with names like CF-4, CG-4, CH-4, or CI-4. The best diesel oil to use is 20W-50. 15W-40 or 10W-40 are also okay.
This is a big deal. It means a Harley engine is like a diesel engine. They both run hot. They both have high pressure. Diesel oils have strong cleaners. They also have additives to stop wear. This proves that diesel oil can work. But Harley says to use it only for a short time. You should go back to Harley oil soon. And this is only for the engine. Do not put diesel oil in the primary or transmission.
4.Warranty and Other Oils
Many owners worry about their warranty. Will using other oils void it? In the U.S., a law protects you. It is the Magnusson-Moss Warranty Act. This law says a company cannot make you use their brand of oil. They can only do that if they give you the oil for free.
This means a dealer cannot deny your warranty claim just because you used AMSOIL. Or Mobil 1. Or Red Line. The company has to prove something. They must prove the oil you used did not meet their rules. They must also prove that the oil caused the problem. So, you can use other good oils. Just make sure it is the right kind for V-twin bikes. And make sure it is the right thickness. Your warranty will be safe. This lets you pick oil based on quality and price. You do not have to use the Harley brand.
All About Oil
To make a good choice, you need to know about oil. The choice between regular and synthetic oil is not just about price. It is about how they are made. It is about how they work in a hot V-twin engine. Words like “motorcycle-specific” are important. They mean the oil has a special mix. This mix is for wet clutches and high pressure. Car engines do not have these needs.
1. Regular Oil vs. Synthetic Oil
The big difference is in the base oil parts. These parts are called molecules. This changes how the oil works. It is very important for heat. Heat is the biggest issue for a Harley engine.
Regular (Mineral) Oil
Regular oils come from crude oil. H-D 360 is a regular oil. The oil is cleaned. But the parts inside are not all the same size or shape. This is a problem in a hot engine. The small, weak parts can burn off. This makes the oil get thick. It can form sludge. The oil stops working as well.
Full Synthetic Oil
Full synthetic oils are made in a lab. H-D SYN3 is a synthetic oil. Their parts are all the same size and shape. This gives them big advantages. These advantages help a Harley engine.
- Better in Heat: The parts in synthetic oil are strong. They do not break down easily in high heat. The oil keeps its thickness. It keeps protecting the engine. This happens even on long, hot rides. Or in traffic. It stops sludge from forming.
- Stronger Parts: Oil parts can be torn apart. This happens between moving gears. Or between the piston and cylinder. This is called shear. Synthetic oils are stronger against shear. They keep their thickness longer. This protects gears and other parts from wear.
- Better in Cold: Regular oil gets thick in the cold. It is slow to move when you start the engine. This can cause a lot of wear. Synthetic oil stays thin in the cold. It moves fast to all engine parts. This protects the engine right away.
- Keeps Engine Cleaner: Good synthetic oils have better additives. These additives clean the engine. They stop acids from causing harm. They hold dirt so the filter can catch it. This stops sludge from building up.
Synthetic Blends
Synthetic blend oils are a mix. They have both regular and synthetic base oils. They are better than regular oil. They cost less than full synthetic oil. They have some of the good things about synthetic oil. But they do not protect as well as a full synthetic oil.
A Harley V-twin engine is air-cooled. It uses oil to stay cool. This makes a strong case for full synthetic oil. Synthetic oil is much better at handling heat. This is a big benefit for these engines.
2.The Special Mix in Oil
The base oil does the main job. But additives fine-tune the oil. Bike oils need a different mix than car oils.
Anti-Wear Agents (ZDDP)
ZDDP is a very important additive. It is Zinc Dithiophosphate. It protects parts that touch with great force. An example is the cam and lifter. ZDDP forms a film on the metal. This film wears away instead of the metal. Older Harleys need a lot of ZDDP. This includes the Shovelhead and Evolution engines. Some oils, like Red Line, have very high levels of ZDDP. This gives the best protection.
Detergents & Dispersants
These additives clean the engine. Detergents stop acids from causing harm. They keep hot parts clean. Dispersants hold dirt in the oil. This dirt includes soot and sludge. The oil carries the dirt to the filter. The filter then removes it.
Friction Modifiers and Wet Clutches
This is very important for bike oils. New car oils have friction modifiers. They help cars use less fuel. But these are bad for a bike’s primary case. They can make the wet clutch slip. This is why you should not use car oil in the primary. Bike oils do not have these friction modifiers. This helps the clutch work right.
3. Oil Ratings (API & JASO)
Oils have ratings. These ratings show they meet certain standards. Two are important for Harley owners.
API (American Petroleum Institute)
The API “S” rating is for gas engines. Each new rating is better than the last. For example, SP is better than SN. But there is a problem for bikes. Newer car oil standards have less phosphorus. Phosphorus is part of ZDDP. This was done to protect car parts called catalytic converters. Less ZDDP is not good for bike engines. This is a big reason why bike-specific oil is better.
JASO (Japanese Automotive Standards Organization)
The JASO T 903 standard is for bikes with wet clutches. It tests the oil to make sure the clutch will not slip. There are two main ratings:
- JASO MA: This is the standard for bikes with a shared oil system.
- JASO MA2: This is a higher standard for better clutch feel.
Any oil you use in a Harley’s primary should be at least JASO MA. This will make sure the clutch works right. This shows that you need to use oil made for bikes.
Other Oil Brands
Harley’s oils are good and safe for your warranty. But other companies make great synthetic oils. They say their oils are even better than the factory’s. Three brands are very popular. They are AMSOIL, Mobil 1, and Red Line. Each brand has its own ideas about oil. Let’s look at them.
1. AMSOIL
AMSOIL was the first company to make synthetic oil for cars. This was in 1972. They are known for using data and tests.
- Products: AMSOIL has a full line of oils for V-Twins. Their main oil is the 20W-50 Synthetic V-Twin Motorcycle Oil (MCV). It is a 3-in-1 oil. You can use it in the engine, primary, and transmission. They also sell special oils for each part. They have a Synthetic V-Twin Primary Fluid. They have a Synthetic V-Twin Transmission Fluid. They say these are even better than using one oil for all three.
- Claims: AMSOIL uses a lot of test data. They post results that compare their oil to others. They even compare it to Harley’s SYN3. They claim their 20W-50 oil is six times stronger than H-D SYN3. This is in a test for shear stability. They also say you can use their oil for longer. You can go twice as long between oil changes. You must use an AMSOIL filter too.
- What Riders Say: Many riders on forums love AMSOIL. It is a top recommended brand. Riders say their engines run cooler. They say their engines are quieter. They also say shifting is smoother. This is especially true when using the special primary and transmission oils.
2. Mobil 1
Mobil 1 is a very famous synthetic oil brand. It is a trusted choice for Harley owners. It is easy to find.
- Product Line: Mobil 1’s main product is the Mobil 1 V-Twin 20W-50 full synthetic oil. They focus on this one great product for V-twins.
- Performance Claims: Mobil 1 V-Twin 20W-50 is made for hot, air-cooled engines. They say it protects well from heat. It keeps the engine very clean. It also stops rust. Like H-D SYN3, it is a 3-in-1 oil. You can use it in the engine, primary, and transmission. This makes it easy for owners.
- Rider Perception: Mobil 1 is seen as a safe and good upgrade. You can buy it in most auto parts stores. This makes it very easy to get. Many riders switch to Mobil 1 first. It is often recommended as a great oil for a good price.
3.Red Line
Red Line is for people who want the very best. Racers and engine builders often use it. They want the best protection. They do not mind the high cost.
- Product Line: Red Line has very special V-Twin oils. They have a 20W-50 oil. They also have a 20W-60 oil for very hot weather or big engines. Red Line says to use special fluids. They sell a V-Twin Primary Case Oil. They also sell a famous V-Twin Transmission Oil with ShockProof®.
- Performance Claims: Red Line uses special base oils. They are called polyol esters. Ester oils are very strong. They are stable at very high heat. Red Line oils also have a lot of ZDDP. This is the anti-wear additive. It is great for older engines or high-stress engines. The ShockProof® transmission oil is famous. It has tiny solid bits in it. These bits cushion the gears. This makes shifting much quieter and smoother.
- Rider Perception: Red Line is seen as a top-level oil. It is for riders who want the best. Many riders with custom or high-power engines use it. The transmission oil is very popular. It is known to stop the loud “clunk” when shifting gears on a Harley.
These three brands have different ideas. AMSOIL is for the owner who likes data. Mobil 1 is for the owner who wants a trusted, easy-to-find oil. Red Line is for the owner who wants the absolute best protection.
This is clear in the “3-in-1 vs. Special Fluids” debate. AMSOIL and Red Line sell special fluids for the primary and transmission. This suggests that a single oil is a compromise. A 3-in-1 oil is very good and very easy. But using special fluids for each part is the best way to protect your bike.
| Attribute | H-D Screamin’ Eagle SYN3 | AMSOIL 20W-50 V-Twin | Mobil 1 V-Twin 20W-50 | Red Line 20W-50 Motorcycle | |
| Base Stock Type | Full Synthetic | Full Synthetic (PAO-based) | Full Synthetic | Full Synthetic (Ester-based) | |
| 3-in-1 Use | Yes, primary application | Yes, but specialized fluids are recommended for optimal performance | Yes, primary application | No, specialized fluids are strongly recommended | |
| Key Marketing Claim | Factory tested, certified, and warranty-approved for H-D motorcycles | Superior shear stability (resists breakdown 6x better than SYN3); extended drain intervals | Outstanding high-temperature protection for air-cooled engines; trusted brand | Ester base stocks for ultimate film strength; high ZDDP content for maximum anti-wear | |
| Target Audience | Warranty-conscious owners; those preferring OEM products; convenience seekers | Data-driven enthusiasts; high-mileage riders; those seeking long-term value | Pragmatic owners seeking a trusted, widely available upgrade from conventional oil | Performance purists; owners of modified or older engines; those seeking maximum protection | |
| Availability | Harley-Davidson Dealerships | Independent dealers; online ordering | Major auto parts stores; mass retailers | Specialty performance shops; online retailers | |
| Relative Price Point | High | High | Moderate-High | Very High | |
4. Other Good Brands
AMSOIL, Mobil 1, and Red Line are top brands. But other good brands exist.
- Maxima Racing Oils: Maxima is a popular brand. They sell oil change kits. The kits have all the oils you need. They also have a filter and O-rings. This makes the job easy.
- Lucas Oil: Lucas is well known in racing. They make good V-Twin synthetic oils. Many riders like them.
- Spectro Oils: Spectro has been around a long time. They are another good choice. Their synthetic oils are seen as very high quality.
- Bel-Ray: Bel-Ray is also an old brand. They sell a full line of V-Twin oils. They have regular, blend, and full synthetic oils.
Oil Plans for Your Engine
The main rules for oil apply to all Harleys. But the best plan can change. It depends on your engine. Harley engines have changed over time. The new Milwaukee-Eight is different from the old Evolution. The oil needs have changed too. You need a plan for your specific engine.
1. New Engines (Milwaukee-Eight, 2017 to now)
The Milwaukee-Eight (M8) is Harley’s newest engine. It has four valves for each cylinder. Some models have oil or liquid cooling. These engines run hotter than older ones. They are also built with tighter parts. This means a high-quality, full-synthetic oil is a must. Harley knows this. The tune-up kits they sell for M8 bikes only have full-synthetic oil.
If you have an M8 engine, use a good SAE 20W-50 full synthetic oil. The oil needs to handle high heat. It also needs to be strong. This protects the engine parts. Some M8 engines can use oil or have other issues. So, check your oil level often. Some riders change their oil more often than the 5,000-mile rule. For the M8, be safe. Use the best synthetic oil.
2. The Workhorse Engines (Twin Cam, 1999-2017)
The Twin Cam engine was used for a long time. It is known to be a strong engine. These engines do not run as hot as the M8. They are a bit more forgiving. So, you have a choice. You can use a good regular oil, like H-D 360. Or you can use a full synthetic.
Many Twin Cam owners use a full synthetic. They say it makes the engine run cooler. It also makes the engine quieter and smoother. This is the engine where the “three-hole” debate is common. You can use one 3-in-1 oil like H-D SYN3 or Mobil 1. This is easy. Or you can use special fluids from AMSOIL or Red Line. This may give better performance. For the Twin Cam, the choice is up to you.
3. The Famous Evo (1984-1999) and Older Engines
The Evolution (Evo) engine is a classic. But it is an old design. It needs special care when it comes to oil. This is also true for older engines like the Shovelhead.
First, there is the “synthetic leak myth.” Some owners of old bikes worry. They think synthetic oil will cause leaks. They think its small parts will get past old seals. This is partly true. But it is not the whole story. Synthetic oil has strong cleaners. It can clean away old sludge. That sludge might have been plugging a small leak. The oil does not cause the leak. It just finds it. If you have an old Evo with old seals, synthetic oil might cause a leak.
Second, there is the issue of additives. The Evo engine needs a lot of ZDDP. This anti-wear additive protects the cam and lifters. Some new synthetic oils have less ZDDP. So, you should use an oil with a lot of ZDDP. This could be a V-twin synthetic oil like Red Line. Or it could be a good regular oil made for these engines.
So, the plan for an Evo is tricky. If you have an old, high-mileage Evo, be safe. Use a high-quality SAE 20W-50 regular oil. H-D 360 is a good choice. Or use a regular oil with high zinc. If you have a rebuilt Evo with new seals, a full synthetic is a great choice. It will give the best protection.
As engines get newer, the oil needs change. Newer engines run hotter. They have tighter parts. This means the best oil choice moves from regular to full-synthetic.
| Engine Family | Recommended Oil Type | Key Considerations | Optimal “3-Hole” Strategy |
| Milwaukee-Eight (2017-Present) | Full Synthetic (Required) | High operating temperatures; tight tolerances; potential for oil consumption. Regular oil level checks are critical. | Better (Optimization): Specialized synthetic fluids for engine, primary, and transmission to maximize protection and performance. |
| Twin Cam (1999-2017) | Full Synthetic (Recommended) or High-Quality Conventional (Acceptable) | Upgrade to synthetic for reduced heat and noise. The central platform for the “3-hole” debate. | Good (Convenience): A single 3-in-1 full synthetic. Better (Optimization): Specialized synthetic fluids. |
| Evolution (1984-1999) & Older | High-Quality Conventional (Recommended for high-mileage, original engines) or Full Synthetic (Excellent for rebuilt engines) | Potential for leaks with synthetics on old gaskets; requires oil with high ZDDP content for flat-tappet valvetrain protection. | Better (Optimization): Specialized fluids are highly recommended. Use a high-ZDDP engine oil and dedicated primary/transmission fluids. |
Making Your Choice
All this info leads to one point. The “best” oil is a choice. It is a choice you make for your bike and for you. We can now make a simple plan to help you choose.
How to Find Your Perfect Oil
To pick the right oil, think about three things. How do you ride? What is the weather like? And how do you feel about bike care?
- Your Rider Profile:
- The Weekend Rider: You ride for fun on weekends. You do not ride a lot of miles. Your engine does not work too hard. A good regular oil is fine. H-D 360 20W-50 is a good, low-cost choice.
- The Long-Distance Rider: You ride long trips on the highway. Your engine gets very hot for a long time. You need an oil that is good with heat. A full synthetic like Mobil 1 V-Twin 20W-50 or H-D SYN3 is a great choice. They are also 3-in-1 oils, which is easy.
- The Fast Rider: You ride hard. You have a modified engine. You want the best protection. You need a top-level synthetic oil. AMSOIL or Red Line are the best choices. You should probably use their special fluids for each of the three holes.
- Climate:
- Hot Climate (like Arizona): Heat is the main problem here. A full-synthetic SAE 20W-50 is the best choice. For extreme heat, you could even use a SAE 20W-60 oil from a brand like Red Line.
- Four-Season Climate (like the Midwest): You have cold winters and hot summers. A synthetic oil is key. An SAE 20W-50 synthetic is good for most of the year. But if you ride when it is near or below 40°F, you should use a different oil. An SAE 10W-40 is better for the cold. The new SAE 15W-50 SYN3 is also a good choice for all year.
- Your Budget and Care Plan:
- By the Book and on a Budget: You want to follow the rules and save money. Use H-D 360 regular oil. Change it on schedule. This is the right path for you.
- Best at Any Cost: You want the absolute best for your bike. You are willing to pay for it. Use a full-synthetic, multi-fluid plan. Use special oils for the engine, primary, and transmission. Get them from AMSOIL or Red Line. This is the best protection you can get.
The Final Word on the “Three-Hole” Plan
So, should you use one oil or three? It depends on what you want. Do you want what is easy? Or do you want what is best?
- Good (The Easy Plan): Use one high-quality full-synthetic 20W-50 oil. Use it in all three holes. H-D SYN3, Mobil 1 V-Twin, or AMSOIL 20W-50 are all good choices. This plan gives great protection. It makes oil changes very simple. This is a great choice for most riders.
- Better (The Best Plan): You want the best performance. You want the quietest shifts. You want the best clutch feel. Then you should use special fluids. This is the best technical choice. Brands like AMSOIL and Red Line say this. Many expert riders agree. A special primary fluid and a special transmission fluid will work better than a 3-in-1 oil.
The Main Point: Use Clean Oil of the Right Type
In the end, the brand of oil is not the most important thing. The most important thing is this: the best oil is always fresh, clean oil. It must be the right type and thickness for your bike and the weather. A bike with fresh, cheap regular oil is safer than a bike with old, expensive synthetic oil. Change your oil on time. This is the best way to make your engine last.
So, here is a simple guide to choosing your oil:
- Good: Follow the owner’s manual. Use H-D 360 20W-50 regular oil. Change the oil and filter on schedule. This is safe and saves money. It meets all warranty rules.
- Better: Switch to a full-synthetic SAE 20W-50 oil. You can use H-D SYN3, Mobil 1, AMSOIL, or another good brand. This is a big step up. It gives much better protection from heat and wear. This is the best choice for most Harley owners.
- Best: Use a full, optimized oil plan. Pick a top-level synthetic engine oil. Then, use special fluids for the primary and transmission. Get them from a brand like AMSOIL or Red Line. This plan is made just for your bike, your climate, and how you ride. It is the highest level of protection you can get.
FAQs for Best oil for Harley Davidson
What is the best oil for my Harley Davidson?
The best oil depends on where you ride. Most Harleys use 20W-50 oil. Always check your owner’s manual. It will tell you the right oil for your bike and the weather.
Is synthetic oil better for a Harley?
Yes, synthetic oil is often better. It protects your engine from high heat. It also helps your bike run cleaner. This can make your engine last longer.
Can I use car oil in my Harley Davidson?
No, you should not use car oil. Bike oil is made for wet clutches. Car oil has additives that can make your clutch slip. Always use oil made for motorcycles.
What do the oil numbers like 20W-50 mean?
The numbers show the oil’s thickness. The first number with a “W” is for cold weather. The second number is for hot weather. 20W-50 is a common oil for Harleys.
How often should I change the oil in my Harley?
You should change your oil every 5,000 miles. Check your owner’s manual for the exact time. If you ride in dusty or cold weather, change it more often.
Conlusition
I used to worry a lot about oil for my Harley. I learned that clean oil is the most important thing. My bike runs much better with a good synthetic oil. It feels cooler and shifts with real ease. Take good care of your bike.