Originally Posted By: jeff78
While I don't disagree with the concerns about shear, it's interesting to note that Honda has recommended 10W-30 for many of their bikes for a good number of years now.
Yep. My Honda NC750 is spec'd for 10w30. I've also run it on 5w30, and it's currently using a 10w40. Honestly, not a bit of difference between them in power or economy, and it's a pretty underpowered bike, so I'd notice any extra HP. If anything, the 10w40 gives a smoother gear change.