Thanks for reading and taking the time for the comments. My understanding is that VW in Europe used to warrant ASTM6751 spec B20 biodiesel for at least the MkIV TDI. I don’t know if they still do. My assumption is that the fuel systems on the VWs in Europe are either the same or similar to the MkIV fuel systems in the US. My comments on the MkIV diesels are from my own testing of ASTM spec biodiesel in my two ’99.5 VW Jetta TDIs with only modified viton return lines. I have 270k miles on one and 320k miles on the other.

Thanks for clarifying about the comments on the newer diesels being conjecture. That’s actually why I specifically referenced the forums and linked to them. I hope that we find that the newer diesels wil run on B20 and greater blends of biodiesel!

Let me know how the 335d handles the biodiesel. Pioneers like you are the ones who will help us know the truth about what works and what doesn’t. I plan on buying the Chevy Cruze diesel when it comes out and will test it with B20 and B100.

-Powell

You have some real misinformation here. VW has never warranted any biodiesel greater than 5% in their vehicles. You say ‘since about 2006′, but that indicates their position has changed, which it has not. In 2007 and 2008, there was no TDI, and in 2009, the new systems came out with DPFs. These are the systems that have oil contamination issues. But your article doesn’t have that level of detail.

The reason they allow up to 5% biodiesel is because the diesel specification was modified such that it can pass with that much biodiesel in it. In other words, “diesel” itself can be B5 and still be considered diesel.

Everything you have said here is just conjecture, and references conjecture by other people on forums – much of which is either based on conjecture on yet more forums, or is baseless.

I know you are a promoter of biodiesel, and aren’t trying to get people to NOT use the fuel; but you should also know that many people have used higher blends of biodiesel with no problems for many miles. It is generally agreed that one “should” change the engine oil more frequently than the recommended 10k miles – but that is a pretty easy trade off for most folks, who have been changing their oil at 3500 or 5000 miles for most of their lives anyway.

Thanks for doing what you’re doing, and please continue to look for facts on this issue. I just bought a 2011 BMW 335d specifically to test B100 and will be reporting the results on my blog (dieselgreenfuels.com/blog) when I get started.

Jason Burroughs
DieselGreen Fuels