I went to the T6 after reading about it. I had run reg. 15/40 in several bikes over the yrs as the write-ups for diesel seemed good. My Futura that was swapped for the 300 got a diet of 15/50 Mobil 1. In the 70s the Guzzi Sport got 20/50 Valvoline. My basis was thicker for bigger slower revers. But now w cars going 0/20 or some such 5/40 seems thick enough. Old and still a bit Clueless!