Robert,
This thread got me reading the fact sheets on biodiesel.org
http://biodiesel.org/resources/fuelfactsheets/default.shtm
And I ran across this info in the 2004 Backgrounder:
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OEM Acceptance Grows. The use of B20 will not void the engine warrnety of any major US diesel engine manufacturer, but NBB is actively working with industry on securing stronger position statements from Original Equipment Manufacturers. A major initiative is also under way to ensure 2007 clean-diesel engines are biodiesel certified.
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While the initiative referred to in the latter half of that statement isn't the same thing as an industry standard, I think it's safe to say that if you drive a modern diesel and fuel it with commercial, ASTM certified B20, the chances of a dealership voiding your warranty for it is pretty much zilch nowadays. The onus is really on the
dealer to demonstrate that the fuel caused your headlight wiring harness, window regulator, MAF, etc. to fail (not that they ever had a legal arguement not to). If you came in with a fried fuel pump, however, it might make things simpler if you kept your biodiesel receipts though. Demonstrating that you use a commercial-grade fuel should pretty much shut anyone up who wanted to scream BIO-USER! (instead of getting on with the task at hand, namely to repair any warranty work requested).
Yes, we've come that far.
~BG