Mikegjax is correct in that the stance has been modified. The issue with biodiesel has to do with regeneration of the diesel particulate filter, not its performance in the diesel engine itself. much discussion of this over on the sprinter-source forum.
I'll make an attempt to summarize what I learned studying this over at sprinter-source, and would ask others to further correct or clarify this...
In general, any diesel fuel not consumed by regeneration gets drawn back into the ENGINE OIL pan where it is expected to properly vaporize as the engine runs. >5% biodiesel has a higher flash point than ulsd, thus it doesn't vaporize as well. the result can be a rising oil level that can damage the engine if left unchecked. when forced to use the higher bio content fuel, use the electronic means of checking your oil level, keeping an eye on it. in general, regens will occur at intervals of 300 miles (approx) if running at highway speeds (and take 15-20 mins to successfully complete, consuming the fuel washed into the dpf by injecting extra quantities into the exhaust stroke of the engine, forcing it into the exhaust pipe where it is captured by the dpf), so each time you fill up, follow instructions for checking oil level. if oil level is high, be prepared to remove some using a manual pump that works thru the dipstick tube. after using >20% bio a lot, shorten the oil change interval.