Link to this post here on my blog about the problems with running biodiesel in modern diesel automobiles, from a MB Sprinter owners forum, leads me to this MB fact sheet  (PDF document).

Biodiesel Information for  Mercedes-Benz Vehicles  2014 Edition

I had a brief argument with a guy in Kansas about all this. The problem here is the religious zeal of the ideology behind it. Weaning ourselves off of fossil fuels is a Good Thing. Mandating bio fuels without regard for what they’ll do to modern engines isn’t getting us there if what people experience is catastrophic engine failure and massive repair bills.  Two winters ago, before taking the drive out to California in my new ‘E’ class diesel, I worried about what I was hearing regarding the proliferation of biodiesel my car can’t drink. What I was told by a mechanic at a Mercedes dealership, was I could always get pure petroleum diesel at an oil company owned filling station because that was all they sold. Truck stops and independently owned filling stations might sell bio, but the oil company ones didn’t. Now the oil companies are not very high on my list of things I approve of, but I found this to be a big relief.  Not any more.  Several states have apparently now mandated at least B10 only, everywhere.  I suspect paying for the repairs to people’s engines when a steady diet of B10 has completely trashed them, let alone paying owners for the lost value of their automobiles, because basically those states have made all the passenger car diesels that can’t take that fuel worthless,  isn’t in the cards.

There’s a lot of bullshit going on here in the biodiesel camp, and a lot of deliberate misrepresentation of what some diesel automobile makers are saying. In the above document Daimler makes it abundantly clear that they do Not approve biodiesel in their vehicles in percentages above B5, and even then only those biodiesel blends that meet ULSD specification ASTM D975. The document says straight up: “Diesel fuels between B6 and B20 or higher pose risks of engine and fuel system damage, and are not approved by  Mercedes-Benz.”

I don’t know how you can interpret that as “Mercedes approves B20 so long as you keep an eye on the oil level” but that is what some people are saying glassy eyed on that MB Sprinter forum. No…what they are saying is if you can’t avoid using diesel higher than B5 (thank you jackass state legislatures!) then here is what you can do to minimize the risk of damage to your engine:

•  Fill up with ULSD (B5 or less) whenever possible, from a name–brand fuel station.
• Regularly monitor your engine oil level if you have to use B20 fuel. (this is because biodiesel has a tendency to accumulate in the crankcase oil)
• Strictly follow the oil change intervals quoted in the instrument cluster and within your maintenance booklet, and use
ONLY engine oils and filters approved by Mercedes-Benz for use in the vehicle.
• If you do not plan to drive your vehicle for several weeks, fill your vehicle’s fuel tank completely in advance with ULSD
fuel. (this is because biodiesel has a tendency to sludge up when it just sits in the tank for not very long periods of time. Even the states mandating B10 or higher are saying during the winter months filling stations can sell B5 because it does not have the cold weather sludge characteristics higher percentage biodiesel blends do.)

That does not constitute approval of B10-B20, it only acknowledges a problem they have no control over…the one H.L. Mencken noted when he said that an idealist is someone who, noticing a rose smells better than a cabbage, concludes it will also make a better soup.