I've run Rotella T-6 synthetic 5w-40 for ever in my Yamaha TW-200. Never any issues with the clutch or the motor. I warm my motor up before riding off, every single time.
For my early model VW TDI diesels up until Vw went to common Rail in 2009, I found that Mobil 1 5w-40 Turbo Diesel Truck made it possible to go 10k between oil changes without having to add any make up oil. That was not the case with the Shell Rotella T-6 5w-40, it needed a quart added every 4000-5000 miles.
YMMV, these were my experiences with the two oils.
