I have two oil questions actually, but I think it's best to keep them separate...

Anyway, the viscocity chart in my owners manual seems like it says more or less anything goes. I've been running 5w30, but I notice when its hot and I've been riding a while, the oil light will begin to flicker on slightly at idle if I sit still. I've had it back to the dealer twice now for this and they can't find anything wrong - pressure was good, they even replaced the sensor for good measure at no charge. Would running a thicker oil like 10w40 likely solve this? Is there a negative side to moving up to a thicker viscocity, other than it possibly cranking slower at startup?

I've seen that Valvoline makes what they're marketing as an ATV oil, but I've only seen it in 10w40 weight.

Thanks~