Unless you're running your engine from cold in an extremely cold environment, the 10w-40 stuff should be fine.
Basically the 10w number is the viscosity rating of the oil at cold winter temperatures and the 40 number is the viscosity rating once the oil has reached running temperature (around 100 degrees). Therefore at normal running temperatures, a 0W-40 oil is no different from a 10W-40 oil. Honda recommend a winter viscosity grade of 0w to 5w as the oil is thinner in colder temperatures, meaning it will coat the engine quicker, and prevent the engine from seizing.
What you need to remember is that the W rating is for very cold temperatures, so using this oil at this time of the year should be fine. I would recommend using the suggested oil in the Winter to help prevent the above seizing scenario.
Part synthetic oils are designed more to be used in older cars that are more susceptible to oil leaks. this is because they have a natural oil base which has more abnormal molecules which cause by products like waxy residue building up around seals, furthermore preventing leaks from seal deformities. As your CTR is fairly new, it would probably benefit more from a fully synth oil, however sticking the stuff you've got in atm is not going to kill the engine.
My advice would be to use the stuff you have atm for the summer and come winter time, drain the engine completely, change the oil filter and replace with a 0W-40 fully synthetic oil.
