Inside, in a pole barn. Keeping it out of the sun is my main motivation. UV will do a number on things.
Mine has started as cold as -35 without using the block heater but I am sure it didnt do it any good. Any time it is below 20 I plug it in a couple hours before I start it when possible, lot quicker start/warm up that way and initial idle is not so rough/harsh sounding.It's in the new garage. Before that it was in a tarped shelter. I use fuel treatment in the winter and while it has a block heater I have only used it twice. I am in central Maine so it can get cold here, but with a little glow plug warming it starts right up.