does switching oil viscosity have any negative effects on the motor itself?

 

From the factory, they pretty much got it right.. 5w-30 on most any Honda. If it snows, since this is in NJ, I'm assuming it does, 10w-30 might take longer to get up to temp to circulate through the engine. Also makes the engine a bit more sluggish all around because of windage losses in the crank with the weightier oil. I would just stick to 5w-30 for all season. If it were hot all the time, 10w-30 would be fine but I don't want sludge in my engine, stick to 5w-30.. Your gas mileage and engine will thank me.