I don't blame the OEMs. We already know that there has been bad bio on the market. Not to mention the fact that there are a bunch of people (like myself) who are brewing up their own bio. VW, Bosch, and the rest of them cannot be held responsible for what we put in our fuel tanks. They designed a 'diesel' car... not a 'biodiesel' car. As many of us know, these cars can run for a long time on biodiesel. Maybe not as long as they do on petro diesel... but maybe they'll run longer! Who knows? It is going to have a lot to do with the quality of the fuel... not just the type of fuel. Unfortunately, the quality of US biodiesel is more hit-or-miss than the quality of US petro diesel.
Although I respect Audi5000TDI's point of view, I have to disagree. Why? First of all, because a lot of us are using higher blends than B5 and our cars are still fine. Also, did VW or Bosch test B1, B2, B3, B4, B5, and B6, then discover that B6 caused some sort of damage that B5 did not? I seriously doubt it. They are being extra cautious about bio (which I don't blame them for), and they are suggesting a blend that is known to be safe. Does this mean that B6 will kill our injection pumps? Of course not. Most of us know that, because most of us (who are reading this forum) have used much higher blends.
Personally, I knew that there was a risk of VW denying warranty claims after I started usign biodiesel. However, I did my research, and decided that it was an acceptable risk. It turns out that we didn't need to make any engine-related warranty claims, because the bio didn't cause any damage! Now, at 80k miles, I am still happily driving along with biodiesel in my tank (although it is only my winter blend of B80).
You never know what's going to happen with an automobile. My friend Al's TDI blew an injection pump at about 5,000 miles. He had NEVER used biodiesel. VW replaced his injection pump under warranty. If he had been using bio, they probably would have denied his claim, even though it had nothing to do with the fuel... just a faulty pump.
mparker326, the reason that VW does not come out with any suggestions for older TDIs is that they have no reason to. They already sold those cars. It doesn't benefit them in any way to put a bunch of money into research on cars that they already sold. Who knows, maybe the next version of the TDI will be approved to use B20, or B100. But before that, we'll been a set of ASTM standards for B100. The current ASTM spec for biodiesel is for use as a 'fuel additive'. Without that, we cannot expect to find high-quality biodiesel at every pump.
Even though I make my own bio, I would like to see the commercial biodiesel industry grow and prosper. I would like to see cleaner, cheaper biodiesel at thousands of 'gas' stations around the country. I would like to see more emphasis on algae-based biodiesel and WVO based biodiesel.
Until all that stuff happens, those of us who choose to use biodiesel will have to live with the fact that VW may not cover any fuel-related problems under warranty.