I ran my 200tdi on vegtable oil only for about a year until the price of veg oil was the same as diesel, had no problem at all just the feint smell of chips.
on diesel it started instantly even in winter on oil it would turn over twice before starting.
i also ran it on bio-diesel and noticed no difference from diesel and noticed it did fill the filter and left some slime in the sedementor, i was told that would happen as the bio-diesel will clear the tank and lines when first used.
however i only paid £400 for the disco and sold it for £270 when the gearbox left for the road.
i'll run my 300 on 50/50 when its finally finished.