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Motorcycle Oil, Primary Fluid & Transmission Fluid: What’s The Difference?

Oil Debate on V-Twin motors requiring three sumps

The Fool Said I Can Use 20W-50 In All Three. What?

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 (Don’t forget about Davidson) 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 the record, AMSOIL recommends AMSOIL 20W-50 Synthetic V-Twin Motorcycle Oil (MCV) in the engine, transmission and primary chaincase on most Harleys (consult the Motorcycle Product Guide at amsoil.com 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.
  • It’s what the upper brass at AMSOIL use in their bikes.

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.

See why the 50 weight qualifies as a 90 in the transmission. 

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.

I don’t think so. My Mechanic always said you have to use different oils.  – That’s partially true…

If you believe this to not be true we make the separates for you. Debate free oil options! And yes, they are more dialed in.. This is why we offer Synthetic V-Twin Transmission Fluid (MVT) and Synthetic V-Twin Primary Fluid (MVP).

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 us to engineer each lubricant for its precise application.

Transmission Fluid

Synthetic V-Twin Transmission Fluid has a higher viscosity than 20W-50 Synthetic V-Twin Motorcycle Oil. A higher-viscosity, or “thicker,” lubricant can help quiet noisy transmission gears and enable smooth shifts. The lubricant develops a slightly thicker fluid film on gears, which provides cushion to help diminish loud “thunks” and gear noise.

Again, we realize that’s what people want and in some cases it’s beneficial to the gears but it’s slightly thicker than the OEM specifications or better put – on the high side of the range. The only real downside other than cost is less efficiency in cooler weather and a change in overall MPG.

Primary Fluid

Likewise, AMSOIL Synthetic V-Twin Primary Fluid is designed only to protect primary chaincase components. Its viscosity is similar to an SAE 50 motor oil. Formulating it as a straight-weight lubricant naturally offers an advantage in shear stability over other multi-viscosity lubricants. (AMSOIL 20W-50 Synthetic V-Twin Motorcycle Oil is absolutely shear stable and will not thin out from mechanical activity.) This helps the fluid remain thicker, which helps it cling to the compensator without being “flung off” as easily for maximum protection. In Harleys, the compensator acts as a shock absorber to prevent engine vibration from affecting the transmission. Compensator wear often leads to a knocking or ticking noise.

Synthetic V-Twin Primary Fluid also clings well to the chain for excellent wear protection. And its wet-clutch-compatible formulation meets JASO MA/MA2 requirements.

Many buy this because some bikes have issues shifting back to neutral. AMSOIL Primary Oil makes it much easier for the linkage to catch neutral when you need it.

One oil or three?

So, which is the better route for Harley owners? Either way you can’t go wrong but examine if you identify with the issues requiring the 2nd choices.

For riders who desire the simplicity and convenience of using one lubricant for all three areas, following our primary recommendation of 20W-50 Synthetic V-Twin Motorcycle Oil in all three areas is the best choice.

For riders who prefer lubricants dialed in for each area of their bikes and don’t mind a few extra bottles of oil lying around the garage, steer them toward our full line of V-twin lubricants.

Either way, they can’t go wrong. 

Ordering 605-274-2580

Quality products are the result of focused effort.

Dan Peterson - AMSOIL Technical Development

This blog entry will be a posting from AMSOIL’s technical development VP – Dan Peterson. Dan is one of the people behind the exciting direction AMSOIL is taking in the enthusiast market.

Dan Peterson - AMSOIL Technical Development

AMSOIL’s Dan Peterson.

AMSOIL is a very fortunate company as we have many loyal customers. I can only guess at all the reasons why people keep coming back to AMSOIL. Maybe it is because they
like the outstanding service they get from their AMSOIL Dealers. Or maybe it is due to the range of products or the personal, hometown service they receive from AMSOIL corporate. It could also have something to do with the commitment from AMSOIL
to always provide the best value available anywhere. When you buy AMSOIL products, you know you are always going to get the best. I am happy that we provide a combination
of reasons for customers to come back again and again. You can call me old-fashioned or naive, but I think people keep coming back because AMSOIL stands apart from this world full of gimmicks, get-rich-quick schemes and heretoday, gone-tomorrow unbelievable
claims. AMSOIL is simply devoted to delivering the best value possible, day in and day out. I would like to have a list of AMSOIL-like companies so I wouldn’t have to search around for who makes the best stuff and who I can count on for the long term.

Since I am the technology guy, I would like to focus on the value that we strive to build into new and reformulated products. Customers buy products based on their perception of the value they will receive from a product and how the product’s benefits compare to the
product’s cost. And there are a lot of choices out there, so your proposition has to continually be better than the next guy’s or you won’t stay in business. So how do we go about continually building new value into AMSOIL products? It starts with Al’s commitment to be the best. This does not mean that we have only one motor oil and it is the best in the world; it means that whether it is OE, XL, European Car Formula or Signature Series, we are committed to being the best in that category. When someone
chooses an AMSOIL product, that customer can be confident it provides the best value possible.

So what special skills do we have that allow us to continually create the best value in each category? Can’t anyone do this? Well, I didn’t grow up in the big city, but it seems to me
that if you are always striving to meet only the minimum requirements while making the most money possible, you get pretty good at making the most money possible on products that barely meet the minimum technical requirements. It is very different at AMSOIL. We are never going to have the cheapest products on the market, and that’s a good thing when you are counting on a thin film of oil to keep your $40,000 new car running
for the next 15 years. We start with a different challenge: How do we make products that significantly exceed technical requirements at a price point that customers can afford.
If you start with this challenge in mind, you get pretty good at making products that significantly exceed minimum technical requirements at an affordable price.

By always pushing the limits of what can be done technically, we can break barriers and build new value into products that couldn’t be done if we focused solely on cost optimization. One of these new plateaus was recently reached at AMSOIL with the first successful double-length sequence IIIG test.
This is an engine test used for API licensing. It runs in a very severe set of conditions, including high oil temperatures and exhaust gas contamination for 100 hours. It tests
the ability of the motor oil to resist thickening and keep the engine clean. Our Signature Series 5W-30 product was tested in a planned double-length test (200 hours) to see if it could reach this summit. Not only did it pass, it did so with flying colors. You can expect to see the results from this test in the very near future. We do not know of a commercially available motor oil that has ever reached this mark. Not that they would be striving toward this goal if they are continually getting really good at making more money by meeting the minimum requirements.

Note – Since Mr. Peterson wrote this the Sequence IIIG test has been published. You can see the results by following this AMSOIL Technical Test Link to the 5W-30 Signature Series Test – OR see all the recent published performance tests using this link.