A high level oil company technician told me that pretty much every oil that does not have the term "Energy Conserving" in the doughnut on the oil container's back side can be used with a wet clutch. He said that most oil companies won't spend the money to get the JASO certification because they have other products that are specifically designed for those motorcycle wet clutch applications. Apparently Shell made the decision to spend the money to obtain JASO certification on some of their Rotella diesel products. It's likely that a high level exec within the company is a motorcycle enthusiast and knew there were plenty of other motorcycle owners who would purchase those proven Rotella oils because they are less expensive than most of the "dedicated motorcycle oils" in the market. Rotella didn't change their formulation of diesel oils so that they would meet JASO requirements, they simply submitted samples of their standard product, paid for the certification testing, and received the approval. The Delvac 5W40 I use in my bikes works great with the wet clutches, and pretty much any oil that doesn't have "Energy Conserving" on the label will work with a wet clutch. Oil companies are in business to make a profit, just like anyone else. They would much rather sell their dedicated 4-stroke, ATV, V-Twin, high performance motorcycle and other similar offerings at elevated prices than their standard labeled automotive and diesel oils. Shell's 4T 10W40 synthetic motorcycle oil sells for $10/quart at Walmart -- that's almost four times the price of Rotella T6! That's not to say that those specialty oils aren't the same as automotive or diesel, as they do usually have additives that provide additional protection for severe environments to prevent shearing and viscosity breakdown. My only point is that, just because the back label of an oil container doesn't have JASO certification, it doesn't mean that it doesn't meet those requirements and won't work with a wet clutch. If it's an energy conserving oil (typically pass car oils 5W30 and thinner), it certainly won't meet JASO requirements. Over the years I've used basic 10W40 Shell and Valvoline car oil in motocross, trail and street bikes and never had a clutch related issue (10W40 is not energy conserving). I'm surprised that Shell and others still make that oil because there are very few passenger cars on the road that still use 10W40. I'd be very curious to see a new oil analysis comparison of that Shell 10W40 and a non-synthetic 10W40 motorcycle labeled oil and see what the differences and similarities are.