The tricky part of cooking oil in engines is that it's higher viscosity / thicker than diesel. So straight cooking oil only really works well in the types of d

The tricky part of cooking oil in engines is that it's higher viscosity / thicker than diesel. So straight cooking oil only really works well in the types of diesel engines that use glow plugs and swirl chambers...where the fuel gets fully atomized despite the high viscosity. Direct injection diesel engines have more trouble with cooking oil, with lots of deposits and gummy build up. The dirty bits aren't a big issue, other than for any fuel filters if you don't filter it first.