Some are, some arent.

Some will run on almost anything, straight veggie oil, old oil, heating oil etc etc.

Some will shit the pump after a very short period of time.

I know a guy who tried once on his 306....turned out it had the wrong pump lol and it died after a few thousand miles running on veggie oil.

If you search SVO type forums I'm sure they can advise better.

But if you're talking red diesel type of thing. Red diesel is excellent quality fuel and any diesel engine will be happy on it.
By comparison over here anyway, buy white from a lot of garages and you havent a clue what your buying as it could simply be laundered diesel.
I'm sure the same thing goes on over there too.

As much I had disbelieved it before, early this year the place I was buying diesel from must have changed their supplier. MPG took a nose dive by about 12-15% ! Asda fuel was the same.
Switched to a different brand, and suddenly mpg was restored. And the original supplier certainly wasnt a cowboy outfit as I had been using them for months and all was fine.

Recently with current brand Ive been getting better mpg than Ive ever had. So even with legit white diesel, there really is a huge difference