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.

Thanks. I imagine the 5w40 would give you a noticable improvement in gas mileage too.