Biodiesel

which can then be used with various software options. The ELM327 Wi-fi Car Diagnostic Interface, for example, can be used with a number of options and may be worth considering. Q Can any of the newer common-rail diesels run on biodiesel? Or are they now relegated to the era of mechanical piston and rotary diesel pumps? William Bamber

A In its pure form, biodiesel is a mixture of vegetable and animal oils which is then combined

with alcohol or methanol to gain the correct consistency and break up the oil molecules. This is called B100 and can degrade certain rubber components and block pump galleries or injector nozzles.

What is normally available is either B20, B15 or B5, which are respectively a 20%, 15% or 5% mix, with the greater mass being made up of standard diesel. Most vehicles can run on B5 without issue, but a check would need to be made with the manufacturer before using any of the higher percentage grades. Normally, using a biodiesel of a higher percentage than 5% will invalidate the vehicle’s warranty. None of the newer commonrail diesels will happily run on biodiesel due to the design of the more efficient and cleaner engines – which is, when you think about it, something of a paradox!