For what it's worth, always use an oil that is rated for diesel engines. It will contain additives to suspend the soot that will come by the rings on any diesel. Normal motor oil cannot suspend the soot inherent in a diesel crank case. The soot particles then have the opportunity to make contact with rods, bearings, etc. Not good. I live near Binghamton, NY and run Delo 400 15-40 in my Cummins/Dodge and the JD-430. They both started well at 10* today. The key to a good starting diesel is a properly rated battery in a state of good charge, extremely clean electrical connections and an absolutely air-tight fuel system. A little Power Service additive (in the white bottle) doesn't hurt either.
greg