Just a quick note on the fuel side, bigger picture stuff: from my somewhat limited understanding of biodiesel production, the producers can easily adjust the flash point and vapor pressure to get it consistent with ULSD. A tiny (read this: tiny, as in TINY, as in 0.05%, yes that's tiny, so please don't FREAK out) amount of methanol or gasoline
can adjust the fuel to be the same as diesel.
Producers know this because delivery trucks sometimes load biodiesel when there is a bit of gasoline still in the truck from the previous delivery. The fuel gets tested after delivery and hmm... Now, for the love of Plato, please do NOT go crazy on me about how bad methanol and gasoline are for diesel engines. Duh, we all know that. We're talking half a % here. AND it's all theory at this point, I'm not in a position to affect your fuel or anyone else's.
So if this is possible, then bio producers or the gov can adjust the ASTM standard, the bio becomes the same as diesel, and there's no issue of unburned un-vaporized fuel on the cylinder walls, therefore no oil dilution. So I propose we find someone with an 09 TDI to run B100 and add 0.08 gal of gasoline at each fillup (tank size 15 gal?) and see their oil dilution results.