[Scratcher]

Originally Posted by chittychittybangbang

Yes, you can't sell a car if fuel can't be used in it. Even if a manufacturer includes a note or disclaimer there are still product standards. A lawyer could give you a technical answer.

The problem with greater than B5 is engine oil dilution. The main difference between the new TDI and older TDI is the post injection combustion. During a DPF regen active cycle, a little bit of fuel is injected after the regular fuel injections. Because of the properties of biodiesel, some more ends up on the cylinder walls and washed into the crankcase. Once there, it evaporates slower than diesel and therefore accumulates. If the fuel is B5, over time the percentage of fuel in the crankcase that is biodiesel goes from about 5% to 10% during a normal oil change interval. The concern is that over B5 lets bio accumulate faster. As an example, B20 might accumulate from 20% bio in the crankcase fuel to 50% bio in the fuel which is over VW's limits.

You can read more about it in the DPF article in the FAQ section. And I know who sold you your TDI

Wouldn't oil analysis balance this out?