The official way (as outlined via TOPIx) is to remove the tank content using an extraction pump, and emptying it from the filler neck. That's the easiest way without having to remove the tank.
That's a lot then.....drain the tank change the filters fill with nice new diesel and carry on. I'm not sure if there is a drain on the tank of a disco 4, but I'm sure someone will be along shortly to verify that. I think halfrauds do a electric pump so check em out. Let us know how you get on.
Well that is strange,for in Scandinavia ,the handbooks recommend adding up to 30% petrol to diesel in winter-I personally add up to 20% petrol to my bio in winter,but then mine is a old 300 tdi