It’s a dumb idea to run straight veggie in this climate if you ask me. Too much effort to try to keep the fuel warm. A blend like slasky suggested is a much better idea.
I’m not convinced it is economically viable to use veg oil if you factor in a reasonable labor rate for time spent screwing with it. But if you use a lot and can make it on a large scale and/or you have lots of free time then it’s certainly viable.
IMO for an application like a compressor its a reasonable idea. For a vehicle, again in this cold climate, I think it’s a not a good idea.