with Kurtis. The big killer is lubrication, which is why oil pan heaters are quite popular with diesel owners in very cold climates. I still have 2 diesels that I run year round, one in a tractor, the other in a large portable generator. As both have an extreme amount of hours on them. I use both an oil pan heater and a recirculation block heater to ensure the oil flows. In -30 deg C (about -20 deg F), I warm them up for at least 5 minutes, then load them lightly until they are at full operating temp. One of the engines has just over 8000 hours, the other is unknown, as the hour meter quit a few years ago at 12,500 hours. neither engine has ever had more than basic maintenance done to it.
I'm not a diesel guy, but have followed the recommendation of 90 year old that ran diesels all his life, and so far it's paying off for me.