We're experimenters and fiddlers by nature. In the winter especially, we like to mix up various blends and test their cold weather characteristics. Here you can see a visual difference from pure biodiesel (B100) on the left to B50 and B20 to B10 on the extreme right.
If you live in a climate where it gets colder than 40 degrees, you'll need to do your own experimenting to see what ratio will run best without any gelling. We've learned through experience that it's better to stay on the lower concentrations. In rural Pennsyvania, it's not uncommon for cold weather days in the 20s and lower--and we use B20 and anti-gelling agents.
Please refer to our Biodiesel in Cold Weather articles for Cold Weather Must-knows.