Rotella T6 -> 5w40 vs 15w40?

[Yata-Garasu_imp]

15W40 might be quite heavy for the CB1100, possibly even under Texas heat.

Rotella T5 is definitely not recommended for motorcycles with a wet clutch.

If you can find T6 10W40 you might be fine.

I used T6 5W40 in the heavy and hot summers in southern Ontario.

There's no T6 in 10w40.

There are a bunch of guys using T5 in their motorcycles at the oil forum Bob Is The Oil Guy. The evidence against using it seems more based on not having the MA letters on the bottle, while the evidence for it seems to be based on actual real world experience.

100 miles in and my CB1100 seems to like it, but I will definitely be keeping a close eye on it, and will update the forum with my experience.

Regarding T5, you could be right with supporting empirical evidence.

Nonetheless, since there is no MA/MA2 certification, there is no assurance that the T5 recipe won't change (small adjustments) and be/remain in favour of wet clutches. Shell won't be responsible for any side-effects since it is not formally approved for general motorcycles. Maybe no certification has something to do with how the T5 semi-synthetic (?) is concocted? Maybe there are other issues that have nothing to do with wet clutches, like burned particulates and sensors/catalyzing, etc. (don't know)

On the other hand, T6 explicitly declares the certification.

Regarding T5, you could be right with supporting empirical evidence.

Nonetheless, since there is no MA/MA2 certification, there is no assurance that the T5 recipe won't change (small adjustments) and be/remain in favour of wet clutches. Shell won't be responsible for any side-effects since it is not formally approved for general motorcycles. Maybe no certification has something to do with how the T5 semi-synthetic (?) is concocted? Maybe there are other issues that have nothing to do with wet clutches, like burned particulates and sensors/catalyzing, etc. (don't know)

On the other hand, T6 explicitly declares the certification.
T5 has Molybdenum in it. Just a touch, about 100 ppm. In higher concentrations Moly is not good for wet clutches, but at the low levels in T5, it shouldn't be an issue.

But that's a good point that Shell could change the formula and not worry about how it affects motorcycles. So far, the T5 10w30 is outperforming both the T6 15w40 and the Honda GN4 10w40.

I thought long and hard before taking the T5 plunge. So far so good, but the jury's still out.

I just got home from running errands, gonna take my "Crow Bike" for a spin!