MOTORCYCLE OIL, PRIMARY FLUID & TRANSMISSION FLUID: WHAT’S THE DIFFERENCE?
Some V-twin motorcycles, like modern Indian* and Victory* bikes, use a shared sump, meaning they use the same lubricant in the engine, transmission and primary chaincase. Most Harley-Davidson* motorcycles, however, use a separate sump for each lubricant. This presents Harley owners with a choice: Use the same lubricant in all three areas of the bike, or use a separate lubricant formulated and labeled for each area. Here, we offer guidance for deciding what’s right for you.
For the record, AMSOIL recommends AMSOIL 20W-50 Synthetic V-Twin Motorcycle Oil in the engine, transmission and primary chaincase on most Harleys (consult our Motorcycle Product Guide for specific recommendations). It offers...
Convenience. Riders buy and install one lubricant. This reduces cost and results in fewer half-used bottles of oil lying around the garage.
Simplicity. Remembering to buy one lubricant is far easier than remembering three.
Great all-around performance in all three areas of the bike.
We formulate 20W-50 Synthetic V-Twin Motorcycle Oil to be an excellent all-around lubricant. It delivers outstanding engine protection due to its proven ability to fight wear, reduce heat, maintain cleanliness and prevent corrosion during storage.
Synthetic V-Twin Motorcycle Oil also boasts a shear-stable formulation. It resists viscosity loss despite the intense pressure and churning action of high-rpm transmission gears, allowing it to deliver reliable transmission protection.
Synthetic V-Twin Motorcycle Oil meets JASO MA/MA2 standards and is wet-clutch compatible for excellent performance in the primary chaincase. Its frictional properties are dialed-in to allow the clutch plates to engage and disengage without loading or slipping for smooth shifts.
Despite these benefits, some riders question the practice of using one lubricant in all three areas of their bikes. They have a difficult time accepting that a motor oil can also protect the transmission and primary chaincase.
For these riders, we offer Synthetic V-Twin Transmission Fluid and Synthetic V-Twin Primary Fluid.
What are the differences?
In essence, Synthetic V-Twin Transmission Fluid and Synthetic V-Twin Primary Fluid are formulated to protect just one area of your bike rather than three. This specificity allows AMSOIL to “over-engineer” each lubricant for its precise application.
Synthetic V-Twin Transmission Fluid has a higher viscosity than 20W-50 Synthetic V-Twin Motorcycle Oil. A higher-viscosity, or “thicker,” lubricant provides some advantage in helping quiet noisy transmission gears and enabling smooth shifts. The lubricant develops a slightly thicker fluid film on gears, which provides extra cushion to help diminish loud “thunks” and gear noise.