AMSOIL vs. Harley-Davidson Oil: How We Perform

Bikers always want to know how AMSOIL products compare to the competition, particularly against Harley-Davidson oil.

It’s no wonder since Harley-Davidson dominates two-wheeled culture despite the resurgence of the Indian brand and the rising popularity of adventure bikes and everything you can do with them.

The company’s founding is a great story. William Harley and Arthur Davidson built their first motorcycle in a 10×15 shed right here in our home state of Wisconsin. While the duo’s 116-cc prototype bike lacked the power to ascend the hills around Milwaukee, it turns out it had the power to reshape American culture.

That’s one reason several AMSOIL employees ride Harleys.

But, what about Harley-Davidson motorcycle oil?

To see how AMSOIL Synthetic V-Twin Motorcycle Oil performs vs. Harley-Davidson oil, check out the performance-test results for yourself.

AMSOIL vs. Harley SYN3

AMSOIL 20W-50 Synthetic V-Twin Motorcycle Oil resists viscosity breakdown 6X better that Harley-Davidson SYN3 Oil.*

Why viscosity matters

Viscosity is the most important property of a lubricant. While it’s defined as “resistance to flow,” it helps to think of viscosity as the oil’s thickness.

Your motorcycle engine, transmission and primary are designed to use oil of a specific viscosity, likely 20W-50 if you’re riding a Harley. The higher the numbers, the thicker the oil. So, a 20W-50 is thicker than the 5W-20 oil you use in your truck.

Oil that’s too thin reduces wear protection

Oil that’s too thin for its application won’t form a durable fluid film on metal components. The oil film protects the bearings from wear, helps keep the piston from scuffing against the cylinder wall, protects the transmission gears, guards against compensator wear and more.

In the transmission, for example, the oil must be thick enough to develop a strong fluid film to cushion the gears against shock-loading and quiet loud “thunks.” This promotes smooth, quiet shifts.

It’s the same story in the primary. The oil must protect the compensator from wear to prevent noise. If it doesn’t, you’ll find yourself on your phone reading the glut of content about Harley compensator noise and how to fix it.

The compensator acts like a shock absorber between the engine and transmission, helping prevent engine vibration from interfering with the transmission. When it wears out, it makes a ticking or knocking noise.

Avoiding this scenario seems easy enough – just use a good oil that maintains its viscosity and forms a strong, protective film on parts.

Motorcycles destroy lesser oils

That’s easier said than done.

Motorcycle engines, transmissions and primaries can be brutal environments that take a toll on oil. The mechanical shearing action of metal parts churning at thousands of rpm (particularly transmission gears) combined with extreme heat can cause oil to lose viscosity and become thinner.

Oil that’s too thin reduces wear protection and can lead to “thunking” transmission gears and a noisy compensator.

And nothing derails your pursuit of freedom on the open road like a noisy bike.

To help avoid these problems, use a motorcycle oil that maintains its protective viscosity, like AMSOIL 20W-50 Synthetic V-Twin Motorcycle Oil. Compared to Harley-Davidson SYN3 oil, it resists viscosity breakdown 6X better for improved protection against compensator and transmission gear wear.*

So, while we love Harley’s rich history of freedom and independence, we’ll stick with AMSOIL Synthetic V-Twin Motorcycle Oil over Harley-Davidson SYN3 oil.

AMSOIL V-Twin Oil Change Kit

*Based on testing of AMSOIL 20W-50 Synthetic V-Twin Motorcycle Oil purchased on 3/19/19 and Harley-Davidson Screamin’ Eagle SYN3 purchased on 3/19/19 in the CEC L45-KRL, ASTM D445 test.


  1. Bought a used 95 883 5 years ago and the p.o. had changed it recently before i bought it with AMSOIL 2050 and i check plugs frequently and they were always rich looking. Just changed oil with what i had which was 2 qts. Of family dollar 2050 and 1 qt. Mobil 1 1550 and new filter which i prefilled. Took for a ride it spun up unusually quicker when i started and battery is 6 yrs old. Checked the plugs and they were clean as when i put em in. I always wire brush the black off when i do but didnt have to this time. I was gonna get the AMSOIL but lack of $$ so used what i had. Im happy. My own mix works ! I use to have full sz ford vans and always the last qt. Of oil i would put in would be mobil 1 and i would put in while eng was running,you could actually hear the engine smooth out and quiet down . mobil 1 best period.

  2. My comments are based on reading the statements of Michael Hanes, Independent AMSOIL Dealer…. who states:
    1. He heard that H-D oil is Mobil 1.
    2. He doesn’t believe that Mobil 1 is a full synthetic….. because “they” put it in new motors.
    3. Use AMSOIL in a new motor…. the rings will NEVER “seat”.
    4. After switching to AMSOIL…. the oil measurement shows 1/2 quart LOW. AMSOIL STAYS at the TOP.
    5. AMSOIL staying at the top eliminates wear…… “and that is a fact”.

    MY Comments to this guy’s statements:
    1. Mobil 1 is obviously a competitor to AMSOIL….. although it IS a fully synthetic motor oil.
    2. Chevrolet installs Mobil 1 full synthetic motor oil into new Corvette engines at the factory.
    3. Piston rings WILL properly BREAK IN with the use of fully synthetic motor oils in NEW motors.
    4. Switch to AMSOIL….. then 1/2 quart LOW. ABSOLUTELY RIDICULOUS and IMPOSSIBLE.
    5. AMSOIL staying in the top end eliminates wear. This definition of “excess oil” is again RIDICULOUS.
    I would say that having a guy like Michael Hanes as an AMSOIL Dealer making FOOLISH and RIDICULOUS STATEMENTS is an absolute DETRIMENT to AMSOIL products in their entirety. Then to publish his statements on your site as an added “selling aid” is IRRESPONSIBLE and not too brilliant.
    I personally have used and recommended AMSOIL V-Twin 20W50 Motorcycle Oil in my Harley-Davidson Motorcycles for many, many years now. WHY? Because it is by far the BEST engine oil on the market for air cooled V-Twins period.
    I have been building high performance Harley motors for decades. These motors are very expensive. They REQUIRE the PROTECTION that AMSOIL synthetics PROVIDE. I use AMSOIL upon a completed FRESH BUILD….. including BREAK-IN miles. I can testify that piston rings WILL break in and seal just fine using AMSOIL. I can also testify that upon tear down and going back into a motor for even more high performance work later….. ALL INTERNALS of the motors look just as good with many thousands of miles on them….. as the day they were built. This is of course considering that engine oil changes had been performed at 2500 mile intervals as I always suggest with my motor builds….. which also consists of oil and filter changes at (50) (250) (500) (750) and (1000) miles on all NEW motors. This number of oil changes may sound EXCESSIVE to some…… but my experience PROVES this WORKS. All new motors LOSE ferrous metal on mating surfaces within. By REMOVING the ferrous metal particles with SEVERAL oil changes up to the first (1,000) miles + using the absolute PREMIUM in engine oil…. AMSOIL. It may cost some dollars to do this…. but the PAYBACK in RELIABILITY, FUNCTION and PERFORMANCE is very much worth the cost and the labor. J. Mac

  3. I have been using Mobil 1 since day one in my ’09 Street Glide. Up until last year or so, I noticed that S&S no longer endorses it? (On the back of the bottles?)
    Also, how does Mobil 1 compare to Amsoil?
    Thanks, Bill

  4. AMSOIL makes my bike run cooler and way quieter! I don’t use anything but AMSOIL in any of my vehicles…motor oil ..transmission fluid it’s far superior.

    1. I don’t believe that Mobil One is a full synthetic oil because they put it in a new motor with the rings not even seated. Do that with AMSOIL and the rings will never seat. also when change the oil the first time with AMSOIL and you start the motor and let it run for a while and then shut it off and check the oil level, it will show a half a quart low. That half a quart of oil is staying up in all of the parts that need the oil on start up therefore eliminating wear on start ups and that is a fact!!!

  5. Years ago, at AMSOIL U, I was told HD did want AMSOIL to be in their bottles, but did want AMSOIL mentioned anywhere on the bottle. The great foresight that Al possessed, made him say absolutely not! We guarantee our oil, and without our name on it, we can not, will not do that. Our integrity was on the line, and should some unscrupulous person decide to try and pull something, as some have in the past, we would have to fight not only the complainant , but HD and the entire population as well. I do believe their oil comes from Venezuela, manufactured by Citco. Please inquire if this is still correct. All I know is, once they change to AMSOIL, I have never had anyone change back, and have had many tell me how well it dropped temps and saved their bikes.

  6. Harley should have done the smart thing: partnered with and recommended Amsoil, which is clearly the BEST oil, instead of trying to make a few dollars by peddling inferior lubricants with their name on the label.

    1. Amsoil can confirm or deny this rumor, but HD wanted Amsoil to produce their HD brand of synthetic oil, but Amsoil refused to make an oil at the spec HD wanted, because it was to far below their base specs for synthetic oil.

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