Engine sound and choice of oil
 

My MB dealers have suggested that if they replace the engine oil in my S500 Model june 2002 ( 9000 miles) with a totally synthetic oil, ( present oil is Semisynthetic) the engine will run quieter.
Could someone please comment whether they think that this is a valid thing to do or whether the dealers are pulling wool over my eyes or ears!
Shall be grateful.

Synthetic was supposed to be there in the first place!
Mods, can we move this to Tech Help, so it gets the attention it deserves?