In terms of viscosity a lot will depend on the condition of the motor, bearing clearances, and the oil pressure you're currently experiencing. And of course your location and whether or not you fire the motor on cold mornings.

Personally, if the 10w-30 provides good pressure then I think its a great choice, if the pressure is a bit low then a step up to 15w-40 or even 20w-50 may be in order. Single weights have their place too--30w...though maybe not in Canada in the winter!