I’ve been running 300 V in my S 1000 RR for years. I have a 20 liter jug of 10W40 and I am just trying to find out for viscosity is acceptable in this engine
Allow me to delve a little bit deeper into the weeds. If you frequently change this or any other decent oil with the JASO MA approval, you’re not going to harm the engine. The problem is when you get to the extremes. “Frequently” in high performance motorcycle terms means every 4 or 5 rides. As members of this group know all too well, oil is WAY cheaper than repairs. I also want to qualify the statement with JASO MA. JASO MA is for sure a motorcycle oil that can be universally used in wet or dry clutch engines.
Just because the oil is Motul 300V, doesn’t mean it has the JASO MA rating. If your 300V doesn’t have the JASO MA, I would use it in your car.
Now we get to viscosity. Oil companies and engine manufacturers have confused this for so long that nobody bothers with actual explaining it. I have more in common with this group of enthusiasts. I would never waste my breath with other groups.
With your particular 10W/40, the 10W is the base viscosity of the oil when cold. In this case, 10 is also the viscosity Petroleum Engineers are TRYING to maintain throughout the temperature range the oil was intended to operate within. As you’ve probably noticed, oil doesn’t get thicker when it gets hot. The myth that 10W/40 goes from a10 weight viscosity to a thicker 40 weight viscosity as it heats up, is simply not true. So what does 40 actually represent? This is where the fuzzy hard to explain part comes from.
Think of 40 as representing the upper ambient and operating temperature range. Everything else being equal, most engines run cooler when the ambient temperature is 60F, and exponentially hotter as the temperature increases. In other words, the engine’s operating temperature will increase substantially higher when the ambient temperature increases from 90F to 100F, then when the ambient temperature increased from 60F to 70F.
Here’s another way of looking at these viscosity numbers. What’s the difference between 10W/30, 10W/40, 10W/50, and 10W/60? All of them have the same base viscosity. W is not Winter. W is is base viscosity at room temperature, 72F. At 0F, 10 weight oil is like jello. At 212F it’s like water. Who’s Winter are we talking about? Winter at Dead Horse Alaska, or Winter in Honolulu? No matter which of these 10W oils you have, the viscosity will be 10 in a cold engine at 72F. We intuitively know the oil does not get thicker when the engine gets hot. We’ve all seen it with our own 2 eyes. So what’s the difference between 30, 40, 50, and 60? (I know you Blokes down under have 70.) Ideally, the oil should maintain 10 viscosity from cold to hot. The second number in a 10W/40 oil, represents the theoretical highest ambient / operating temperature the oil can maintain the base viscosity of 10. In other words, 10W/30 will maintain the base viscosity of 10 up to a ambient operating temperature of about 60F. 10W/40 maintains 10 in a fully warmed up engine and approximately 70F ambient temperature . In your case, 10W/40 would typically be a good viscosity for England, where it rarely gets to 90F or 100F. 10W/50 maintains 10 up to approximately 80F. 10W/60 maintains 10 up to 90F. If you’re regularly riding in ambient temperatures above 90F, you should consider 15W/50 or 15W/60. High ambient temperatures means the engine will also be operating at significantly higher temperatures. High ambient temperatures mean the base viscosity should also be higher. Whenever internal engine parts with tight tolerances get real hot, the oil viscosity needs enough film strength to keep these parts from micro welding. Film strength is measured as the HTHS (high temperature high shear). HTHS (film strength) increases with the base viscosity. 20 weight oil has a higher HTHS than 10 weight oil.
If you have a high performance engine that tends to run high oil temperatures (250F and above), you should use a 20W/60. (Note: Oil temperature and engine temperature are not the same thing. Oil temperature is more important. The typical API Group 3 synthetic oil begins to oxidize at about 260F. Group 4 can handle 290F. Group 5 Ester synthetic can handle 330F. At these temperatures high base viscosity is extremely important.)
To summarize; I could never see the point of 10W/40 oil. Why take the risk when 10W/40 and 10W/60 300V cost the same. 10W/60 will hold up better it the day gets hot. If you always ride where the ambient temperature is 80F to 100F, the base viscosity of 15W60 would be the best. You have a high performance hot engine. If you ride when ambient temperatures are above 100F, I would use 20W/60. Your 10W/40 would be adequate if you ride with ambient temperatures between 35F and 60F. Not the most pleasant, but that’s where engines run the best.
I’ve only hit the high points. I know the centistokes on Material Data Sheets contract what I just said. Don’t get me started on that.
There’s nothing like a cool evening ripping the Pacific Coast Highway south of Big Sur. Epic!