I had intended running mine on bio diesel as in the UK we are allowed 2000 litres for "personal use" tax free. The idea was to go on a course, source a supply of used oil, then produce my own. I suspect there would be a problem with the DPF.
Making your own involves some serious filtering to remove debris and using some unfriendly chemicals to reduce the viscosity. Because of the warning I shall not be trying it out before the warranty expires.
Reading council used to run some of their busses on cooking oil, it was like driving behind a chip shop.