Yes or no, as I'm hearing differing opinions.

 

Bit late now as the Fabia has just had one for the first time in 11 years, and it's definitely running quieter.

Snake oil, read about this poor chaps tale of woe...

 

http://www.pistonheads.com/gassing/topic.asp?h=0&f=23&t=1616894

Oil Flush, followed by new oil, is not a bad thing as long as you get rid of all the flushing oil and don't leave it kicking around.

On really abused/ignored engines, it could cause problems as the muck might be holding it together, but I used it many times on old diesels at 5/6000 mile intervals (Which was the service interval then)

As always be careful with the car, check it's suitable for modern engines and don't do it too often (IMHO).

I have to say, on the MK2 Octy, I just did 9/10k service intervals instead and didn't bother flushing as the oil was never that dirty.