Harley-Davidson And AMSOIL Motorcycle Oil Filter Micron Ratings Comparisons.

Amsoil harley oil filter

Recently a reader asked: I’ve been researching Amsoil motorcycle oil filters for my Harley-Davidson motorcycle. Harley-Davidson has oil filters that will stop particles down to 5 microns, while AMSOIL motorcycle filters only stop particles down to 20 microns. I thought that AMSOIL oil filters were supposed to be one of the better filters out there? Why are Harley filters so much better?

Our answer: The oil filter micron ratings provided by both AMSOIL and Harley-Davidson “Super Premium5” oil filters is like comparing apples to oranges. Each company is measuring their micron ratings on completely different scales. Therefore, the micron numbers are not at all comparable.

AMSOIL offers their motorcycle oil filter ratings on an “absolute” scale. Based on this measurement, their motorcycle oil filters are 98.7% efficient at stopping particles that are 20 microns in size or larger. This is a considered to be a very strong efficiency rating.

For reference, a decent automotive oil filter would stop 98.7% of particles 30 microns or larger.

Harley-Davidson provides their micron numbers on an “nominal” scale. Their nominal claim of “5-microns” with their “Super Premium5” oil filter is not telling the whole story. Filters makers claiming ultra-low nominal micron ratings aren’t mentioning the “efficiency”.

Let’s be clear. Harley-Davidson Oil Filters are definitely not removing 100% of particles down to 5-microns. This would make the oil filter so restrictive that it would go into by-pass mode every single time you rolled onto the throttle. Under most all riding conditions, that would be like having no oil filter.

What is the Difference Between “Nominal” And “Absolute” Oil Filter Ratings?

Absolute filter ratings are determined under controlled testing. The absolute filter rating is shown as 98.7% of particles of a stated diameter being stopped by the oil filter. In the case of AMSOIL Motorcycle Oil Filters, they stop 98.7% of particles measuring 20 microns in size or larger.

Nominal ratings such as the 5-micron rating touted by Harley-Davidson has zero meaning without mentioning efficiency. Chances are high that the H-D filters are about 50% efficient at 5 microns. Where a Harley 5-micron oil filter would score in an absolute filter micron test is anyone’s guess.

What Is a Micron?

A micron is a unit of measurement that is 0.001 millimeters or 0.000039 inches. For example, bacteria are 2 to 3 microns in diameter and a red blood cell is 5 microns. The diameter of human hair averages 70 to 80 microns.

Bottom Line

To sum up the Harley-Davidson And AMSOIL Motorcycle Oil Filter Micron Ratings Comparisons, Harley oil filters might be well-built and near the top of the heap. But it’s very hard to tell. The nominal 5-micron rating touted by Harley-Davidson has no meaning without mentioning efficiency while Amsoil is very clear.

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Amsoil 20w50 & SAE 60

Harley Davidson and Amsoil

It’s no secret the Harley-Davidson owners are a loyal bunch and quite particular about how they care for their motorcycles. So it’s no surprise that some are hesitant to use anything other the house brand of Harley-Davidson Screamin’ Eagle or H-D 360 motorcycle oils. But we have been witnessing a quiet revolution in this area over the past decade as large numbers of riders are moving to AMSOIL 20W-50 or SAE 60 Synthetic Motorcycle Oils for their rides and raving about the discernible benefits of cooler operation, smoother shifting and reduced oil consumption.

How Does Harley-Davidson Oil Compare to AMSOIL Synthetic 20W-50 and SAE 60?

AMSOIL has conducted several head-to-head tests against Harley oils over the past few years. The latest comparisons show that AMSOIL delivers superior motorcycle oil.

AMSOIL 20W-50 Synthetic vs. Harley-Davidson Screamin’ Eagle 20W-50

In the chart below, we see a four-ball wear test using the ASTM D-4172B protocol. The AMSOIL 20W-50 shows a wear scar diameter of 0.40mm, while the H-D Screamin’ Eagle 20W-50 sustains a wear scar diameter of 0.59mm. The Screamin’ Eagle 20W-50 wear scar is 47.5% larger than the AMSOIL 20W-50 result. How does this affect wear control in your engine? This result proves that AMSOIL 20W-50 is vastly superior at delivering boundary lubrication protection in your engine, transmission and primary chaincase. The chance of sustaining wear damage due to metal-to-metal contact is greatly reduced. A note about the 4-ball wear test. It is a legitimate ASTM testing procedure and not to be confused with the fraudulent one arm bandit test.

Amsoil 20w50 vs Hd screamin' eagle 20w50

AMSOIL SAE 60 vs. Harley-Davidson H-D 360 SAE 60 Motorcycle Oil

In the SAE 60 motorcycle oil comparison, AMSOIL SAE 60 and Harley-Davidson HD-360 SAE 60 motorcycle oils were subjected to the High-Temp/High-Shear using the ASTM D 4683 test procedure. This test demonstrates an oil’s ability to maintain viscosity protection under high temperatures. As you’ll note in the graph below, the AMSOIL SAE 60 Motorcycle Oil’s viscosity is 11.26% higher than the HD-360 SAE 60 Motorcycle Oil after the conclusion of the test. This means that the Harley oil was susceptible to shear down, while the AMSOIL SAE 60 viscosity was steadier. This translates into stable and consistent protection under extreme heat and loads.

Amsoil SAE 6o vs HD 360 SAE 60

Which AMSOIL Product for My Harley?
AMSOIL 20W-50 Synthetic Motorcycle Oil is recommended for the following Harley Davidson applications.

Amsoil 20w50 Harley oil

Amsoil 20w50 Evolution 1340 & all Twin-Cam models-

Use in engine, transmission and primary chaincase. A secondary recommendation for the transmission is AMSOIL Severe Gear 75W-110 Gear Oil. Ironhead, Evolution Sportster and V-Rod models- Use in engine and transmission.

Amsoil SAE 60

AMSOIL SAE 60 Synthetic Motorcycle Oil is recommended for the following applications. Flathead, Knucklehead, Panhead and Shovelhead models-Use in engine and transmission.

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