Start with the old thread(s) on cold weather starting.
Really I wouldn't expect any issues starting until the temperature drops below 40F. Along with heating the coolant, it helps to drain the fuel-water separator regularly, also consider adding the regular (white jug) power service diesel fuel "arctic" additive.
I had Bobcat install a block heater when I first took delivery, does wonders with starting when very cold, but I don't bother with it when the high temperature of the day is above freezing. Installation requires removing the threaded plug from the engine (you'll lose some coolant, and get air in the coolant system), but is DIYable. Also be forewarned that you'll need to know the thread size for your engine before you order a block heater -- not all Brutus engines take the same diameter!

Photo Credit: danmac67
Really I wouldn't expect any issues starting until the temperature drops below 40F. Along with heating the coolant, it helps to drain the fuel-water separator regularly, also consider adding the regular (white jug) power service diesel fuel "arctic" additive.
I had Bobcat install a block heater when I first took delivery, does wonders with starting when very cold, but I don't bother with it when the high temperature of the day is above freezing. Installation requires removing the threaded plug from the engine (you'll lose some coolant, and get air in the coolant system), but is DIYable. Also be forewarned that you'll need to know the thread size for your engine before you order a block heater -- not all Brutus engines take the same diameter!

Photo Credit: danmac67