A lot of it depends on what the bio was made from. Soy based bio will gel at a higher temp than Canola based bio. I'm running B-80 right now with temps in the high 20's. If I see that the temps are going to get lower, I switch over to B-50.


Try putting some of your bio in a clear jar with a thermometer in it, and place in your fridge or freezer, then watch and see what temp it starts to cloud up.