Enlighten us...:bigcrowd:
I've got your enlightenment "OVAH-HEEER"
The recommendation for liquid cooled engine lubricant is less subjective to the temperature range of ambient air temperature, thus 10w30-10w40 will cover your requirements, versus an air cooled engine which actually dynamically-reacts to ambient air temperature more radically.
Most petroleum distillate lubricants add friction modifiers to allow for better wet-clutch operation, and lubricant reactions to the friction built up between wet clutch plates simply causes reactions at the microscopic level that alter the lubricants abilities to do it's job efficiently and effectively. Whereas synthetic lubricants are built to minimize friction at more levels effectively reducing engine operation temperatures by their circulatory abilities (moving the heat downstream), as well as their ability to lower frictional coefficients (less heat buildup at load bearing surfaces). Lowering the frictional coefficients allows the materials to maintain their original structural integrity, as much as keep load bearing surfaces more within their original operational limits.
This is the important part, as the parts maintain their original limits there is less propensity for wear to allow tolerances to increase, thus, lowering the available pressure of the lubricant at different locations within the engine. This, in turn, disallows all components to be protected "all" the time.
Petroleum distillates have proven to offer great protection at lower rpm, but as engine HP increases providing increased torque, the potential for load bearing components to become damaged due to fling-off or thinning viscosity usually becomes the culprit. "Wear". Synthetic lubricants maintain a more stable viscosity at higher rpm, and temperature control is also equally effected by the minimization of friction even at higher rpm and load. Thus, less wear, over the long haul at much higher rpm ranges. It really has much to do with the elemental structure of the compounds that we call lubricants, and how "they" react to thermal break-down via friction and the "work" of running around all the galleys and journals inside the engine. Some parts of the engine are actually cooler inside than in other parts like the cylinder walls, clutch plates, or bearing surfaces.
Also, synthetic lubricant is an easier recyclable allowing for reproduction of a quality lubricant for various purposes compared to the enormous work of breaking down a petroleum lubricant through heating, filtering, and disassembling the original lubricant profile back to it's basic forms just to start building it back up again.......
"AND NO, I DIDN'T COPY AND PASTE THIS OFF OF SOME WEB PAGE........."
"You've been schooled boys...." :oldcool: .. "Ya' HEARD ????".......
That means, to you and me, that our beloved bottom-ends, our cylinder walls, our ring faces, our cam / tappet surfaces, all our bearing surfaces, "and" our wet clutches are bathed in a lubricant that is unaffected by how much "friction" we throw at it..... 
