Hmm....Tried my T Reg Tolly on straight cooking from Sainsburys, just to see if it would be OK in an emergency and yes it was fine , mpg slightly down, top speed still the same, smelled like a chippy though. Previously I have run (for many hundreds of miles) on straight cooking oil (doesn,t matter what kind) a Rover 600 SDI, a Rover 218SLD (Pug motor) and a Landrover Series 3 Diesel. I also tried parrafin (greenhouse heater fuel - clear like Vodka) and various combis of all three fuels, the only observations were - starting took an extra turn or two on straight cooking oil, the Landrover was very quiet (for a 1950s design) on straight parrafin and the Pug just ate it all up with no change in either performance or MPG, by the way I don,t hang about, the 600 particularly was used to commute every weekend along the M4 and there was no difference at 110Mph. Of course we havent really had any bad winters for ages and a really cold spell may have gummed up my filters had it caught me out, but it didn,t and I got a lot of cheaper motoring and experience of other fuels should there be another fuel crisis/strike.