I would think that bio-diesel is probably OK to use in your VW during the summer, but would be hesitant to use it much past November as the risk of Gelling is significant.
You can mix Bio with Regular but I am not sure how much kerosene you can add to it to keep it form gelling at sub-zero temps.
The trouble with bio-fuels is that they don’t have the same BTU content as the stuff that comes out of the ground.
I can’t imagine that you have all that much bio-fuels in your area unless it’s mandated by your state. There is none of the bio fuels in my area, Western NY. The state mandates E10 gasoline, and they do mandate that the pumps be posted with the entanol content, and methanol too. So that was my concern with the removal of the E10 label form the pump.
The only diesel within 30 miles of me is biodiesel or truck diesel that have nozzles that do not fit my car.
Biodiesal gets mixed with the oil in the car and can ruin the engine.
Not recommended by dealer or manufacturer of VW