The most widely discussed and important variable with running waste oil is temperature. With the change in season comes some rather significant changes in temperature. The significant change will happen when temperatures drop below the cloud point of the vegetable oil. Cloud point is when dissolved or "melted" solids in the oil, such as wax, begin to separate from the oil and solidify. Cloud point is dependent on the type of oil. With biodiesel, cloud point will vary on the type of oil used to product the biodiesel. See the charts below as an example. The information has been gleaned from the internet from some cursory research.
