Go to any John Deere Ag or Industrial dealer--they have the John Deere Break-In oil you need. It is 10W-30 viscosity. I would run it for 1000-1500 miles, then change to a good 10W-30 oil. The main atvantage I see to synthetics is the cold oil flowability and I would recommend a synthetic if you are going to be using the vehicle in sub-freezing weather.
