Interesting oil discussion. Let me add some points to ponder:
1. Diesel Engine oils, only use API CI-4 Plus certification. CI-4 Plus is rated for Turbo Diesels that is used in engines with higher revs capability. Most diesel engines are high torque but red lines pretty low. Oils tends to foam up and cause bubbles if they are beaten by moving parts. CI-4 Plus reduces the foaming tendencies. Foam and bubbles aren't good when placed between metals to metals as the air is not a good lubricant or gives protection. I believe the Fully Synthetic Shell Rotella is CI-4 Plus rated.
2. Car engine oils: As said, don't use Energy Conservation rated oil (xW30 oils and lighter viscosity) as the Friction Modifier additives which can cause the bike clutch to slip. On Non-energy conserving oils, car oils may not have shear stability. It won't last as long when a 50 weight oil is reduced to a 40 weight oil and to 30 weight sooner. Having said that, some cheapo bike oil of mineral class also does not exhibit shear stability. (when you find that after 1000km of usage, the gears seems not wanting to shift properly).
3. The best oils is: the one that you tried and find it to last long (smooth engine, easy gear changes, doesn't hurt your pocket).
I put in a 20W40 mineral bike oil after 100km with the factory fill. It lasted about 1300km when I could not get to 1st gear from N at a traffic stop. Fortunately, after the 7th attempt, it engaged and off I went....went straight home for the oil change and put in Fully Syn Castrol Power 1 Racing 10W40 which my bike buddy raves about. Let's see..