Rotella T6 -> 5w40 vs 15w40?

[Yata-Garasu_imp]

I used Rotella T6 5W40 with no known side-effects or extra noise - in fact, the lump was quieter and gear shifting remarkably smoother compared to GN-4. Sub-zero winter riding also benefited being 5W and synthetic.

I would have never considered 15W40 for the CB1100, especially for cooler riding weather.

I've used Rotella T6 synthetic for years in all my bikes with good result. When I got my 2013 CB1100 the transmission was a bit noisy and the shift from second to third balky at times. This continued with the 2nd an 3rd oil changes while I was using the Honda brand synthetic 10W-30. I got a factory service manual which said that 10W-40 oils were an acceptable alternative so next change I went back to my old favorite Rotella 5W-40. That was the end of the balky shift and a slight reduction in noise. Whether the Rotella oil was the solution or the transmission finally broke in I don't know. All modern oils are good but the Rotella can be found for so much less than branded motorcycle oils.

I've used Rotella T6 synthetic for years in all my bikes with good result. When I got my 2013 CB1100 the transmission was a bit noisy and the shift from second to third balky at times. This continued with the 2nd an 3rd oil changes while I was using the Honda brand synthetic 10W-30. I got a factory service manual which said that 10W-40 oils were an acceptable alternative so next change I went back to my old favorite Rotella 5W-40. That was the end of the balky shift and a slight reduction in noise. Whether the Rotella oil was the solution or the transmission finally broke in I don't know. All modern oils are good but the Rotella can be found for so much less than branded motorcycle oils.
Yes. And the fact that my Shadow 750 runs noticably better on Rotella T4 than on Honda oil tells me that Honda is good at engineering motorcycles, while Shell is good at engineering motor oils.

I was looking at the 15w40 simply because of the increased shear resistance, and because the T6 supposedly flows very well at low temps for a 15w oil. If you folks are using the 5w40 T6 with good results, I am willing to go that direction too.