Oil usage of this engine is neglible since there's only one labyrinth in the cold section of the engine, and that's pressurized with bleed air. I'm using genuine turbine oil for lubrication in a closed-circuit system (the rotor spins at 160,000rpm). The oil tank is the modified "hip flask", installed directly below the engine.
The engine is designed to run on plain Jet-A1 fuel or kerosine / paraffine (and that's what's actually stored in the veggie oil container...
). Since the combustor is of the vaporizing type, heavier oils and vegetable oils as fuel are problematic. Provided, a bigger combustor with a bigger volume is installed, bio fuel operation should be possible.
But anyway, efficiency is ridiculous. When I started work on this project, the best power-to-weight ratio was the main objective (you probably guess where the journey was supposed to go...). To achieve a half-way decent fuel economy, a recuperator would have to be added in order to recover some of the exhaust heat. Whatsoever, some 5kW of electrical power out of a 2kg (plus accessories) package is quite impressive.
Anyway, it's still a prototype and there are many improvements that would need to be applied to turn it into a viable product...