Is anyone running any other weight oil than 10w30 in there G4200?
Your G4200 lawn tractor has a 2cylinder 424cc engine which works pretty hard. It is one of the smallest Kubota engine sold in North America. I run Rotella T6 synthetic 5w-40 in mine. This is easily the best oil on the shelf in Walmart. (Some folks would argue that T6 is one of the best motor-oils sold.)
Do not be dissuaded by the 5w.... this is the viscosity at 0F (It is very unlikely you will be using your lawnmower at that temperature anyway so it does not even matter) The full-synthetic of T6 will ease starting and protect where other oils give up.