Best oil for Harleys? AMSOIL vs Harley Oil

Who makes oil for Harley-Davidson's?

There are several oil companies that produce oils recommended for Harley-Davidson bikes. All Harleys come factory-filled with either Screamin' Eagle SYN3 Full Synthetic 20W-50 or conventional H-D 360 20W-50. According to Harley, all their bikes with a Twin Cam 110 engine are shipped from the factory with Screamin' Eagle SYN3.

According to the most recent safety data sheets from Harley-Davidson's website, both H-D branded motor oils are manufactured by Citgo in Houston, Texas.

Other 20W-50 and similar oils that are used by Harley riders include:

• AMSOIL Synthetic V-Twin 20W-50
• AMSOIL Synthetic SAE 60 V-Twin Oil
• Mobil 1 V-Twin 20W-50
• Redline 20W-50 Synthetic Oil
• Bel-Ray 20W-50
• Royal Purple V-Twin

What is the best oil for Harley-Davidson's?

Well that's a loaded question. If you asked 10 different people, you might get 10 different answers. Regardless, we'll break down manufacturer-provided specifications in the sections below and round up any independent lab testing that has been done between popular Harley motor oils.

AMSOIL vs. Harley Oil

Harley's SYN3 is regarded as their best oil, being their only fully synthetic engine oil. How does that stack up against AMSOIL?

As of early 2024, AMSOIL 20W-50 V-Twin Motorcycle Oil resists breakdown 6X better than Harley-Davidson SYN3, providing more protection against compensator and transmission gear wear. Both oils were purchased on 1/26/24 and and the test performed was the CEC L45-KRL, ASTM D445 test.

Best Motor Oil, Primary, and Transmission Fluid for Harley's

How long does Harley synthetic oil last?

For most bikes, Harley recommends changing the motor oil, primary, and transmission fluid after the first 1,000 miles. And then the motor oil every 5,000 miles, the primary fluid every 10,000, and the transmission fluid every 20,000 miles.

Harley does not indicate different drain intervals between their H-D 360 conventional motor oil and the SYN3 synthetic oil.

If you choose AMSOIL, you can stretch these intervals quite a bit. lf using AMSOIL 20W-50 V-Twin Oil (which they also recommend to be used as primary and transmission fluid) along with an AMSOIL oil filter, they recommend doubling the drain interval.

Use for up to twice the motorcycle manufacturer change interval (miles/hours) or one year, whichever comes first, in engines, transmissions and primary chaincases. For Big Twin Harley-Davidson transmissions only, follow the Harley-Davidson recommended drain interval for synthetic oil of up to 20,000 miles (32,187 km) or one year, whichever comes first. If not using an AMSOIL Motorcycle Oil Filter, change the filter at standard intervals.

For off-road use, change AMSOIL 20W-50 Synthetic V-Twin Motorcycle Oil at motorcycle-manufacturer-recommended intervals

Racing or modified engines are excluded from extended-drain interval recommendations. Oil changes are at the owner’s discretion.

Can I use full synthetic oil in my Harley?

You certainly can use full synthetic motor oil, transmission fluid, and primary fluid in your Harley. Using full synthetic oils like AMSOIL V-Twin Oil as your motor oil, primary, and transmission fluid, can double the drain intervals for all three and resist viscosity breakdown up to 6X better than Harley's SYN3 motor oil.

Is primary oil and engine oil the same on a Harley-Davidson?

Most Harley's have three separate sumps for the motor oil, primary chaincase oil, and transmission fluids. There are a handful of oils that are designed to be used in all three. AMSOIL 20W-50 V-Twin Oil and Harley's SYN3 Oil were designed to be used in all three sumps.

However, if you want maximum protection, it's typically best to purchase purpose-specific fluids for all three. AMSOIL makes dedicated V-Twin Primary Fluid and V-Twin Transmission Fluid for Harley riders who prefer using purpose-build fluids designed as a step up in performance from the fluids that come factory-filled in your Harley.

Does AMSOIL void Harley warranty?

No, using AMSOIL or any other aftermarket oil does not automatically void your Harley warranty. The only circumstance where using AMSOIL could void your warranty is if it can be proved that the use of AMSOIL directly caused damage to your Harley (like using a completely incorrect weight of oil).

Consumers in the U.S. are protected by the Magnusson-Moss Warranty Act which grants consumers the right to install aftermarket parts without automatically voiding warranties.

Conclusion

In conclusion, AMSOIL makes some of the best motor oils and fluids for Harley-Davidson's and other V-Twin motorcycles. If you're looking for the best 3-in-1 oil to use in the motor, primary chaincase, and transmission, AMSOIL 20W-50 V-Twin Motorcycle Oil is the best choice.

Resources

• Harley SYN3 Motorcycle Oil 20W-50 Safety Data Sheet
• Harley H-D 360 20W-50 Motorcycle Oil Safety Data Sheet
• AMSOIL 20W-50 V-Twin Motorcycle Oil
• AMSOIL V-Twin Primary Chaincase Fluid
• AMSOIL V-Twin Transmission Fluid