Response from VW was as expected. They "strongly recommended not to use" biodiesel because of a lack of legislation over biodiesel fuel quality and specifications.

The 2GO kit, as it turns out, is not dealer fitted but a factory order option, which consists of a fuel heater, (extra?) filters and "various technical modifications". I suppose, we are not really at any risk of gelling which eliminates the need for a fuel heater. As for the filters... I found some extra information in this discussion paper on biodiesel released by the federal government in 2003 (http://www.deh.gov.au/atmosphere/fue...esel-paper.pdf) about the specific qualities of (bio)diesels which may contribute towards...

- injector clogging
- contamination of engine oils
- accelerated corrosion in fuel lines
etc.

One thing I hadn't thought about was that biodiesel has metallic contaminants, because of the alkali catalyst that is used (NaOH, KOH etc). Petro-diesel standards don't cover this. There are biodiesel standards established since 2003 (http://www.deh.gov.au/atmosphere/fue...sel/index.html) but are they legislated? Do biodiesel producers even have anything to comply with?

They may well be self regulating the quality of bd at present, but who knows?? More digging is needed I think.