If you filter it well, you actually can run a diesel engine from waste cooking oil directly (but it's not great for it, which is why it's often converted to bio

If you filter it well, you actually can run a diesel engine from waste cooking oil directly (but it's not great for it, which is why it's often converted to biodiesel or HVO/HEFA). The hydro-processing that HEFA/HVO (the kind of fuel used in the above trial) goes through is mostly for cold handling properties, viscosity, etc. - it actually makes it basically chemically identical to the fossil derived hydrocarbons that are normally used, which is pretty cool and interesting.