Problems......that is what heavy equipment and truckers run all year? Sounds like you are buying into FRED's theory on a 5W40 being too thin "no offense Fred", but that is pure hogwash. I run the stuff "all year" in both my bikes and it works fabulous. Bigger and more powerful engines run on 20 weight oils "factory spec", so any 40 weight oil in a motorcycle is gonna work fine.
Sorry Poke, but Fred has a point with the low viscosity as it affects the right-angle drive gears and the trans gears. T6 starts with a viscosity at the low range of a 40 weight and it shears to a 30 weight very quickly in the C14. I've seen oil analyses that show RTS T6 very close to a 20 weight after 3000 miles in a C14.
Now I don't know about you, but I don't want those gears in the right-angle drive to the drive shaft running in a 20 weight oil. These are basically the same kind of gears that are in the rear drive unit and they run in 75w-90 gear lube.
So, I'm gonna have to agree with Harmon on this one. There are better oils for the C14 engine than RTS T6 5w-40 such as Rotella 15w-40. If you change it every 3000 miles, I don't think there would be any major problems with T6, but I wouldn't use it for extended oil change intervals.