Krohsis
Active Member
Since I have come to the forum, I have read many posts on motor oils. I have also learned from past experience that discussing motor oils on a forum is like discussing politics or religion at a family reunion, one should just not do it. But part of a forum is to share information for the betterment of everyone. So, I will be breaking the cardinal rule to never talk about oil.
The two main recommendations on the forum with respect to the topic of which oil to use in the Vmax are to stay away from synthetic oil, and to use Shell Rotella, an oil designed for diesel engines. Neither are the best advice.
The reason people are warned to stay away from synthetics by some on this forum is to prevent clutch slippage. It is true that synthetic motor oil is slipperier than petroleum oils, that is ONE of MANY reasons why synthetic oils perform better than petroleum oils. But just because an oil is synthetic isn’t a reason to give up all the good it brings to the table because of the fear of clutch slippage. There are MANY oils that are synthetics that are formulated for motorcycles that run wet clutches (clutches that live in the motor cases and are exposed to the motor’s oil) and don’t cause clutch slippage. Those oils can be found by looking at the label and seeing if they have the JASO rating. JASO stands for Japanese Automobile Standards Organization. It was accepted as the global standard for the T903 specification for clutch slippage in wet clutches in 1998. Also, JASO comes in 2 formulations, MA and MA2. MA doesn’t have as much grip as MA2, so it comes down to feel in the clutch lever as to which you want (more bite with MA2 at the point of hookup). Or if you are running a modified high torque/high HP motor you might want MA2. Most will be happy with MA. So, when you are buying a motor oil for a bike that has a wet clutch look at the label and make sure it is JASO approved, that goes for either synthetic or petroleum, and you won’t have clutch slippage.
The reason I believe you are doing your motor a disservice running Rotella is because it is an oil designed for diesel applications, not motorcycle applications. Rotella is a GREAT oil in a diesel engine. It has a long following in the diesel truck world, and I have used it on a limited basis in my diesel trucks. It also has a JASO rating on the label, so that is why it doesn’t cause slippage. But the demands on an oil in a motorcycle are very different and much more rigorous than a diesel motor. But the biggest reason to run a motorcycle specific oil over something like Rotella is our Vmax engines have the transmission lubricated, cooled, and protected by the motor oil. That is where a motorcycle specific oil comes into play.
Most modern motor oils have Viscosity Index Improvers in them. They are polymer molecules, like polymethacrylates (PMA) polyisobutylene (PIB), radial polyisoprene and olefin co-polymers (OCP), that change the viscosity of the oil and make the oil thicker when hot. For example, a 10W40 motor oil (if you don’t know, the W stands for winter(cold), 10W is the weight of the oil. But as the oil gets warmer the VI Improvers change size to make the oil thicker, up to 40 weight. This is great technology, and it works flawlessly, until it gets exposed to the shearing forces in a motorcycle transmission. The shearing forces in just motor part of our Vmax are not terribly hard on the oil. The forces in rod journals, main bearings, cam lobe faces, pistons and rings don’t have the ripping and tearing of the VI Improvers that the gears in the transmission subject them too. Motorcycle oils have additives to protect and prolong the life of the VI improvers and the oil. So, if you do use a non-motorcycle oil you should change your oil more frequently because over time the ability of the VI improvers to do their job is reduced. There was an article in Motorcyclist magazine a few years ago, and they recommended, if you run an automotive oil in your motorcycle, you should change at intervals no longer than 1000 miles because of what the transmission does to the oil. The process of VI Improvers being torn apart by the transmission over time reduces the viscosity of the oil. For example, the oil may start out as a 10W-40 but over time, it may become 10W-35, and then a 10w-30, and if it goes long enough it could be way out of the original viscosity specs.
I don’t want this post to get too long, so I only really touched lightly on the subject. There is plenty of data and articles on the subject too if you care to get more info on this topic.
The two main recommendations on the forum with respect to the topic of which oil to use in the Vmax are to stay away from synthetic oil, and to use Shell Rotella, an oil designed for diesel engines. Neither are the best advice.
The reason people are warned to stay away from synthetics by some on this forum is to prevent clutch slippage. It is true that synthetic motor oil is slipperier than petroleum oils, that is ONE of MANY reasons why synthetic oils perform better than petroleum oils. But just because an oil is synthetic isn’t a reason to give up all the good it brings to the table because of the fear of clutch slippage. There are MANY oils that are synthetics that are formulated for motorcycles that run wet clutches (clutches that live in the motor cases and are exposed to the motor’s oil) and don’t cause clutch slippage. Those oils can be found by looking at the label and seeing if they have the JASO rating. JASO stands for Japanese Automobile Standards Organization. It was accepted as the global standard for the T903 specification for clutch slippage in wet clutches in 1998. Also, JASO comes in 2 formulations, MA and MA2. MA doesn’t have as much grip as MA2, so it comes down to feel in the clutch lever as to which you want (more bite with MA2 at the point of hookup). Or if you are running a modified high torque/high HP motor you might want MA2. Most will be happy with MA. So, when you are buying a motor oil for a bike that has a wet clutch look at the label and make sure it is JASO approved, that goes for either synthetic or petroleum, and you won’t have clutch slippage.
The reason I believe you are doing your motor a disservice running Rotella is because it is an oil designed for diesel applications, not motorcycle applications. Rotella is a GREAT oil in a diesel engine. It has a long following in the diesel truck world, and I have used it on a limited basis in my diesel trucks. It also has a JASO rating on the label, so that is why it doesn’t cause slippage. But the demands on an oil in a motorcycle are very different and much more rigorous than a diesel motor. But the biggest reason to run a motorcycle specific oil over something like Rotella is our Vmax engines have the transmission lubricated, cooled, and protected by the motor oil. That is where a motorcycle specific oil comes into play.
Most modern motor oils have Viscosity Index Improvers in them. They are polymer molecules, like polymethacrylates (PMA) polyisobutylene (PIB), radial polyisoprene and olefin co-polymers (OCP), that change the viscosity of the oil and make the oil thicker when hot. For example, a 10W40 motor oil (if you don’t know, the W stands for winter(cold), 10W is the weight of the oil. But as the oil gets warmer the VI Improvers change size to make the oil thicker, up to 40 weight. This is great technology, and it works flawlessly, until it gets exposed to the shearing forces in a motorcycle transmission. The shearing forces in just motor part of our Vmax are not terribly hard on the oil. The forces in rod journals, main bearings, cam lobe faces, pistons and rings don’t have the ripping and tearing of the VI Improvers that the gears in the transmission subject them too. Motorcycle oils have additives to protect and prolong the life of the VI improvers and the oil. So, if you do use a non-motorcycle oil you should change your oil more frequently because over time the ability of the VI improvers to do their job is reduced. There was an article in Motorcyclist magazine a few years ago, and they recommended, if you run an automotive oil in your motorcycle, you should change at intervals no longer than 1000 miles because of what the transmission does to the oil. The process of VI Improvers being torn apart by the transmission over time reduces the viscosity of the oil. For example, the oil may start out as a 10W-40 but over time, it may become 10W-35, and then a 10w-30, and if it goes long enough it could be way out of the original viscosity specs.
I don’t want this post to get too long, so I only really touched lightly on the subject. There is plenty of data and articles on the subject too if you care to get more info on this topic.
![Bovemanx Motorcycle Phone Mount Holder, [150mph Wind Anti-Shake][7.2inch Big Phone Friendly] Bike Phone Holder, Motorcycle Handlebar Cell Phone Clamp, Compatible with iPhone 16 Pro Max Smartphones](https://m.media-amazon.com/images/I/51F+1sontPL._SL500_.jpg)
