im now running on 100% bio. I have 4 diesel vehicles and so bio is the only sensible choice for me. I can chuck it in any of them without any worries.
If its just the landy - a tdi or N/A then SVO works a treat. - 10% petrol mixed in and your away. But getting SVO at a reasonable price is becoming more and more difficult.
Black diesel - illegal and you will be fooked if you get caught
WVO - need to add kit to your vehicle to be able to run it and if your going to do that you might as well just go to bio and not worry about the **** thats in the fuel then.