Chris, it may be worth getting the injectors recalibrated at the same time
I know WVO and Bio give slightly less MPG than DERV.
WVO seems to be available commercially at around 70p per litre but then you have the cost of 50, 20 and 10 micron filters and a few barrels for a very basic set up plus an inline heater for winter minimum.
With the cost of extra fuel filters and the alterations, I might stick to DERV as its not doing enough miles to warrant it
Wish the HDI could cope though
