I am posting this short article to help anybody thinking of converting. We have used bio-diesel on 5 vans and a forklift for a year equating to over 100,000 miles and have the following observations. 1. It is not cheaper as fuel consumption is higher. 2. Whilst the fuel is fine i feel the modern engine is so specifically designed to burn a light mineral oil, the fuel system struggles with the heavier bio-diesel. 3. The bigger or less sophisticated the engine the better 4. As a result we have had more breakdowns and costly repairs. 5. It is likely that the competition for land will be lost by the bio-fuel as it is very land intensive and the demand for cereal and protein for human food on the world market is growing rapidly. 6. Recycled cooking oil is a finite resource and emulsifies too easily with water, which in turn renders it unusable as a reliable fuel source for transport. As a result we feel we cannot bear the extra costs and the vagaries of supply when we are trying to maintain reliable deliveries to our customers. However the massive reduction in health threatening and unpleasant pollution do make it a serious option for use in diesel forkilifts used in doors. For the vans it is back to the drawing board. LPG? Bio-ethanol?