Harley Davidson Oil and Wear Test Comparisons

Harley-Davidson "Genuine" Motor Oil
Wear Comparison

In Industry Standard Four-Ball Wear Testing, Harley Davidson’s Own "Genuine" Motor Oil Produces the Highest Wear Scar vs. Other Leading Motorcycle Oils!

Synthetic Oil 4 Ball Wear Testing

The latest test results comparing the new Harley Davidson Screamin’ Eagle Syn3 to AMSOIL 20W-50 Motorcycle Oil are in. The most notable differences between the two products are in the 4-ball Parameter 3 wear test.

In the original 4-Ball Parameter 1 test the Harley Davidson "Genuine" motorcycle oil left a wear scar of 0.40 mm while the AMSOIL 20W-50 Synthetic Motorcycle Oil left a wear scar of only 0.35 mm.

In the more severe 4-Ball Parameter 3 test (shown above) the Harley DavidsonScreamin Eagle Syn3 left a wear scar of 0.70 mm while the AMSOIL 20W-50 Synthetic Motorcycle Oil left a wear scar of only 0.39 mm. This data indicates that the Harley Davidson SYN3 oil leaves a wear scar 79% higher than the AMSOIL motorcycle oil.

Harley Davidson recommends using their new 20W-50 Syn3 in the engine, transmission and primary chaincase. While you may certainly use the AMSOIL 20W-50 motorcycle oil as a replacement for the Harley Davidson Syn3 in all three areas, AMSOIL’s alternative recommendation is for using their 20W-50 Synthetic Motorcycle Oil for the engine crankcase, Severe Gear 75W-90 Synthetic Gear Lube for the transmission and the 10W-40 Synthetic Motorcycle Oil for the primary chaincase.

For Sportster 883cc and 1200cc motorcycles, the AMSOIL Synthetic 20W-50 Motorcycle Oil is recommended for both the engine and transmission.

Older Shovelheads, Panheads and Flatheads the recommendation is to use AMSOIL SAE 60 Synthetic oil for optimum performance and protection.

In respect to Harley Davidson petroleum oil, Harley Davidson maintains that you use their "Genuine" Motor Oil, yet Harley-Davidson doesn’t make their own motor oil, which is manufactured by Sunoco.

AMSOIL Synthetic 10W-40 and 20W-50 motorcycle oils give motorcyclists what they need: Superior wear protection for high-stress motorcycle engines and transmissions that stay clean and deposit-free.

Please Beware: many Harley Davidson dealership technicians are telling customers that synthetic motor oil is "too slippery" and can cause flat spots on roller bearings because the bearings won’t turn. That myth is scientifically and chemically untrue. The person telling you that is not a tribologist (lubrication engineer) and knows absolutely nothing about the science of lubrication. The fact that Harley now markets their own brand or synthetic oil (SYN3) contradicts their own false rumors.

Synthetic motor oils are no more "slippery" than petroleum motor oils. The tractive coefficient, which is the measure of the case with which a lubricant facilitates sliding, is essentially the same for both petroleum oils and synthetics. Synthetic motor oils are also used in many production and racing cars that have sophisticated roller follower technology and they have absolutely no problems whatsoever with roller bearings not turning.


AMSOIL synthetic 10W-40 and 20W-50 motorcycle oils give motorcyclists what they need: superior wear protection for high-stress motorcycle engines and transmissions and clutches that stay clean and deposit-free.

  • Runs cooler—reduces crankcase temperature.

  • Superior 12+ TBN synthetic formulation provides long service life and maximum protection against engine wear.

  • Slipperiness and Wet Clutches

  • Recommended for all V-twin and other motorcycle engines requiring an API CD, JASO MA, SG-CG or SH-CD oil.

10W-40 High Performance Synthetic Motorcycle Oil

20W-50 High Performance Synthetic Motorcycle Oil


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