What Oil Should I Run in My Bike?

“What oil should I use?” This question has been asked thousands, if not millions of times since Gottlieb Daimler put an internal combustion engine in a frame with two wheels in 1885. Unfortunately, the answer you typically get when you ask that question is “Well, it depends”. Depends on what? Oil is oil, right? I enlisted Alex Josefson of Spectro Performance Oils to help answer this age-old question.

The President of Spectro Performance Oils, Alex Josefson, knows a thing or two about oil. His grandfather, Robert Wehman, founded Spectro Oils in 1966, and the company has been family owned and operated ever since. By leveraging his knowledge from his work solving the fuel/oil mixture issues at Saab America (yes Saab used to offer 2-stroke cars in the US), Robert was able to bring that technology and development to the forefront of the motorcycle industry at a time when 2-stroke bikes were booming. However, development didn’t stop at 2-stroke oil, and Spectro has developed hundreds of products over the years that have become staples in the power sports industry.


Sean Moore (SM): What sets Spectro Oils apart from the dozens of other oil brands available for the power sports industry today?

Alex Josefson (AJ): Spectro Oils is the oldest motorcycle specific oil company on the market today in the US. Our company was founded in 1966 with the mission of bringing the best oils to our customers, and our focus has not changed. Today, 95% of our business is in the motorcycle/power sports industry, and we continue to be a leader in that segment. The other 5% of our business is focused in the classic car and performance engine segment.


SM: There’s a lot of talk about the different groups of oils out there. Help us understand what each group is and what it means.

AJ: There are 5 different groups of oil. Groups I, II, and III are mineral based oils which are refined from crude oil. Without getting too technical, the groups are as follows:

  • Group I oil’s are base oils lightly refined from crude oil.
  • Group II oils are more refined than Group I, but share similar properties.
  • Group III oils are highly refined for a more pure base oil.

Group IV and V oils are true man made synthetics:

  • Group IV oils are polyalphaolefins (PAOs). PAOs are able to handle a wider temperature range and really perform well in high heat and high stress applications. They resist shearing which means that your viscosity is less likely to be deteriorated by wear. This allows for longer change intervals.
  • Group V oils consist of all other man made synthetics that are not PAOs. These can include silicones, esters, polyalkylene glycol and others.


SM: So now that we understand what oil groups are, what should I run in my bike? Group III or Group IV? Mineral oil, synthetic blends, or full synthetic?

AJ: Different situations call for different oils, and what you are looking for in an oil can dictate what you use in your bike. Here’s a breakdown of synthetics, synthetic blends, and mineral oils and when you should use each.

  • Synthetic oils are ideal for:
    • Extreme heat or cold
    • Riders that put more than 5,000 miles on a year
    • Extreme use such as high reviving situations, “spirited” riding, etc.
    • Helping to keep air cooled engines at a lower operating temperature during stop and go riding
  • Synthetic blends are ideal for:
    • Moderate climates
    • Riders that put 3,000-5,000 miles on their bike per year
    • Providing some benefits of both mineral and synthetic oils, while being moderately priced
  • Mineral oils are ideal for:
    • Moderate climates
    • Riders that put less than 3,000 miles on their bike per year
    • Older bikes that were designed for mineral oil use
    • Riders that are looking for a lower cost option


SM: What is your recommendation for oil change frequency?

AJ: You should always try to follow the manufacturer’s recommendation. However, even if you don’t put enough miles on your bike in a year to need an oil change following their guidelines, we recommend that you change your oil at least once a year, preferably before putting the bike away for winter storage. This will remove any contaminates from the engine so that they are not sitting in the motor throughout the winter months.


SM: When someone searches the web for what oil is the best they will inevitably come across a company touting their results from a “4-ball wear test”. What is the 4- ball wear test and is it important when deciding which oil to use in our beloved Harley?

AJ: The 4-ball wear test was originally developed to assess the effectiveness of different lubricants/greases for bearings in air compressor motors under high pressure. While this test can be an indicator of the performance of an oil under test conditions, it does not really correlate to real life performance under high temperatures and low pressures. An air cooled Harley engine typically sees oil pressures of around 30psi, which is much less than the nearly 500psi that can been inside and air compressor motor.

There are countless different oils that can be effectively and safely used in your Harley. It is important to ensure that you are using oils made specifically for motorcycles, as traditional car oils may not have the proper additives needed for proper operation in a motorcycle engine, transmission, or primary. Spectro is a company that has been in the powersports industry longer than anyone else here in the US, and they offer an excellent product in their Platinum or Golden 20w-50 for any Harley on the road today. You can order your Spectro Oil Kit here, which will have everything you need for a total fluid change in your Harley! Click here to learn more about Spectro Performance Oil and what they have to offer for your Harley.