You won't have gelling problems with any of the blends in use today. You can get into some handling issues with 100% biodiesel. There are also some misting problems, and concerns with seals and other parts of the fuel systems. You could burn 100% biodiesel no problem if you wanted to, but you might get into some interesting problems while doing it. If you would get in a truckload to blend, be careful handling it in large quantities. It creates a vapor that can be oxygen limiting in enough quantity. Sent one guy to the emergency room. Chads