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Harley Primary Oil Capacity Revealed (All Engines and Sizes)

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The roar of a Harley engine brings an unmatched thrill to the enthusiastic road warrior, but like any unyielding beast, it needs its proper nutrition. For your Harley, this lifeblood is the primary oil—the elixir that intensively lubricates and cool its hard-working components. But, do you know how much oil your bike needs for a healthy ride? Balancing your Harley’s prime oil capacity is as intricate as its mechanism. It varies across all engines and sizes, making it a pivotal factor in your motorbike’s performance and longevity. This comprehensive guide revealing the true Harley primary oil capacity is your roadmap to unlocking the secret formulas. With insightful knowledge and handy tips, we take you beyond the user manual and straight to the heart of your Harley Davidson. Let’s gear up, throttle down and revel in the sweet melody of a well-oiled ride.

Looking for motor oil? Harley Davidson Oil Capacity Revealed (All Engines)

Evolution Engine Series Primary Oil Capacity (82ci)

The blockhead (Evolution engine) from Harley Davidson

The Evolution engine series is one of the most celebrated Harley-Davidson engines. Known for its robustness and reliability, the 82ci Evolution engine requires precise oil maintenance to function optimally.

Although the oil capacity can vary slightly based on the bike model and year, the primary oil capacity for the 82ci Evolution engine is approximately 32 ounces (946 ml). This measurement, however, should ideally be confirmed with the manufacturer’s specifications in the bike’s manual.

What Weight of Oil Is Recommended for Evolution Primaries?

The oil viscosity or weight plays a critical role in the overall engine performance. For the Evolution engine series, a 20W-50 synthetic oil is recommended. This oil weight ensures smooth operation, reduces friction, and provides excellent temperature stability.

What Brand(s)?

When it comes to brand selection for your Evolution engine, AMSOIL Synthetic V-Twin Primary Oil comes highly recommended. This brand is known for its superior protection and performance, especially in extreme heat conditions. However, it’s always advisable to consult your bike’s manual or a trusted mechanic for specific brand recommendations.

Twin Cam Engine Series Primary Oil Capacity

Here's a picture of the Twin Cam 96ci engine from Harley Davidson.

The Twin Cam engine series is a more advanced and larger engine compared to the Evolution series. It includes the Twin Cam 88, 96, and 103.

Twin Cam 88

The Twin Cam 88 engine has a primary oil capacity of 32 ounces (946 ml). This is the general rule, but it’s always a good practice to confirm with your bike’s manual.

Read more: Twin Cam 88 Oil Capacity (Fully Explained + Primary)

Twin Cam 96

Moving up the ladder, the Twin Cam 96 engine has a slightly higher oil capacity. The primary oil capacity for this engine is around 34 ounces (1005 ml).

Read more: Harley 96 Primary Oil Capacity (The Full Explanation)

Twin Cam 103

The largest in the Twin Cam series, the 103 engine, has a primary oil capacity of 38 ounces (1123 ml).

Read more: Harley Davidson 103 Primary Oil Capacity (Full Explanation)

What Weight of Oil Is Recommended for Twin Cam Primaries?

For the Twin Cam engine series, a 20W-50 synthetic oil is typically recommended. This viscosity ensures the engine runs smoothly and efficiently across various temperature ranges.

What Brand(s)?

For the Twin Cam series, the AMSOIL Synthetic V-Twin Primary Oil is a trusted brand. It’s engineered to provide superior protection and performance, particularly in extreme heat conditions.

Milwaukee Eight Engine Series

The 117 engine from Harley Davidson, part of the Milwaukee Eight engine series.

The Milwaukee Eight (M8) engine series is the latest in Harley-Davidson’s lineup. This series includes the M8 107, 114, and 117.

M8 107

The M8 107 engine has a primary oil capacity of 34 ounces (1005 ml). This is a standard measurement, but it’s always best to confirm with your bike’s manual.

M8 114

For the M8 114 engine, the primary oil capacity is slightly higher, at 38 ounces (1123 ml).

M8 117

The largest in the M8 series, the 117 engine, has a primary oil capacity of 42 ounces (1242 ml).

Read more: Harley M8 Primary Oil Capacity (All Engine Sizes Explained)

What Weight of Oil Is Recommended for Milwaukee Eight Primaries?

A 20W-50 synthetic oil is generally recommended for the Milwaukee Eight engine series. This oil weight ensures optimal engine performance across a wide range of temperatures.

What Brand(s)?

For the M8 series, AMSOIL Synthetic V-Twin Primary Oil is a reliable choice. It’s formulated to provide superior protection, particularly in extreme heat conditions.

Know this: understanding your Harley-Davidson’s primary oil capacity and the recommended oil weight is essential for optimal bike performance and longevity. Always refer to your bike’s manual for specific recommendations and consult a trusted mechanic if you’re uncertain. Ride safe!


How much oil is in a Harley primary?

The amount of oil in a Harley primary typically ranges around 1 quart (32 ounces), but this can vary slightly depending on the specific model. It’s recommended to consult the owner’s manual of your motorcycle for the exact capacity.

Can I use 20W50 in my Harley transmission?

Yes, 20W50 oil can be used in the transmission of many Harley-Davidson models. This oil is commonly used for its viscosity range, suitable for both the engine and transmission. However, always check your motorcycle’s owner’s manual for the manufacturer’s recommendations.

Can you use gear oil in Harley primary?

While some gear oils may be compatible, it’s generally recommended to use primary-specific oil or a motorcycle-specific oil like 20W50 in the Harley primary. The primary oil should provide the right balance of friction and lubrication for the clutch and gears.

What kind of oil goes in the transmission of a Harley-Davidson?

The transmission of a Harley-Davidson typically requires a high-quality motorcycle transmission oil. Many riders use 20W50 motorcycle oil, but specific formulations designed for transmission use are also available. Consult your bike’s owner’s manual for the recommended type of oil.

Can I use 75w90 in my Harley transmission?

Yes, you can use 75w90 oil in the transmission of some Harley-Davidson motorcycles. This gear oil is often chosen for its viscosity and protective qualities, especially in high-stress or high-temperature operating conditions. As always, refer to your Harley’s owner’s manual for the best guidance on oil selection.