Can 15W-60 Motorcycle Oil Replace SAE 60?

AMSOIL is no longer offering their SAE 60 Synthetic V-Twin Motorcycle Oil in Canada. The reason for this decision was low sales. Most motorcycles exclusively requiring an SAE 60 motorcycle oil are well over 40 years old. AMSOIL V-Twin SAE 60 will still be offered in the US.

The Harley-Davidson Knucklehead, Panhead and Shovelhead engines use SAE 60 engine oil. Here are the model years that Harley-Davidson offered these engines.

• Knucklehead- 1936-47
• Panhead- 1948-65
• Shovelhead- 1966-84

While AMSOIL is no longer offering the V-Twin SAE 60 motorcycle oil, AMSOIL does offer a very viable option.

A Replacement For SAE 60 Motorcycle Oil

A good replacement for straight-weight SAE 60 motorcycle oil is AMSOIL 15W-60 Synthetic V-Twin Motorcycle Oil. Is a multi-grade oil is suitable for a classic motorcycle engines and transmissions? Absolutely.

Why were straight-grade engine oils used back in the day? The reason is that straight-grade oils were the only reliable way to prevent shearing or thinning-out back then. Multi-grade oils were in their infancy and had to employ primitive “viscosity-index improver” ingredients that were very prone to shear-down. This was especially true in the face of high heat or use in transmissions.

Engine oil technology has advance greatly in past couple of generations.

AMSOIL V-Twin Synthetic 15W-60 is incredibly shear-stable and immune to thinning-out. The 100% synthetic formula delivers a very wide operating temperature range and iron-clad shear stability.

How Does 15W-60 Differ From SAE 60 Motorcycle Oil?

Here are the kinematic viscosity numbers measured in centistokes at 100°C and 40°C for the AMSOIL V-Twin SAE 60 and 15W-60 motorcycle oils.

SAE 60
100°C- 23.4 cSt
40°C- 190.2 cSt

15W-60
100°C- 23.1 cSt
40°C- 164 cSt

As you can see, the viscosity of these two oils are identical at 100°C. Therefore, at operating temperatures, you are getting equal 60-weight viscosity from both products. The kinematic viscosity of the 15W-60 is lower at 40°C. This means that the 15W-60 will deliver better flow at start-up.

Let’s dig a little deeper and look at high-temperature/high-shear viscosity testing numbers measured at 150°C. This testing protocol shows how well a motor oil maintains its viscosity under extreme conditions. The AMSOIL V-Twin SAE 60 result was 7.08 centipoise (cP), while the V-Twin 15W-60 scored a similar 6.9 cP. In other words, both products had virtually the same ability to resist shearing and thinning-out in high temperatures.

Conclusion

AMSOIL V-Twin 15W-60 offers the exact same viscosity protection as the V-Twin SAE 60 product. The only significant difference is that 15W-60 offers a bit faster oil flow at start-up. We would call this an advantage. All without the risk of being beaten down into a thinner oil under hot operating conditions.

Where to buy AMSOIL 15W-60 Synthetic V-Twin Motorcycle Oil? We can offer it at wholesale prices. Contact us for pricing using the form on this page or call us at 1-800-748-5781.