I picked up a 5 gallon bucket of used oil from a donut shop. It is a solid when they put it in the fryer and it turns back solid around 90F. So as an experiment I made a Liter test batch. It was interesting because even though it was used it titrated at 1Gram per liter. I did heat the oil to liquefy it. It made biodiesel very quick. The glycerin dropped out in about 2 minutes when I quit stirring. This biodiesel is good to run in the summer, but the cloud point is to high to run in cold weather.
Solid Veggie oil: (lard/shortening)
Liquified after heating:
Biodiesel from the above:
Solid Veggie oil: (lard/shortening)
Liquified after heating:
Biodiesel from the above: