I am in Kelowna, BC where it is pretty mild and at my oil&filter appointment next week, I am adding a stick-on pan heater to my 2005 cdi.
First couple of years I had the car it was garaged. Next two, I used a magnetic heater but they suck IMHO. Last winter it was fairly mild and I used a folding smart garage. This winter, I will be ready with my electric oil pan heater!
If you have it, use it, is my advice. The diesel's heater is very slow to warm up, so you will be more comfortable. And your car will last longer too!