According to the 2010 MB Fluid application manual, which is actually from 06/05/2008 according to StarTekInfo web page (see picture below), saying 2003-2010 on the bottom not old info, attached by you drivbywire, you ML and GL with or w/o differential locks call for MB Gear Oil Part No. A001 989 33 03 10 - which is 75W85 check posted information by Noodles and also picture posted by me from Star Service, but you probably read the first page only never going further in that manual like everything else we been discussing here. Be very careful, you do not have enough protection there at low temperature with 85W90. You learn one thing and that is it 85W90, even you cannot change your mind when reading something different. In addition, no, my information is probably more recent than yours is, because the picture from Star Service DVD says ®2007 Mercedes-Benz, LLC on the bottom, but I left it out when resized it (can be PM'd upon request). In addition, why you keep changing your opinion: first, you say that 85W90 has cSt of 153, now you are presenting Mobilube HD-A which is also conventional with cSt 184, I think that you did not read the top of the page, where it says that both oils are been formulated from base oils instead of synthetic basestocks. Why do you thing that MB says that the new oil 75W85 can be used on older cars manifactured before 2001 "without reservations". My guess is that they found that it provides sufficient protection when replace 85W90 or 75W90.
All the B*** S**** aside read everything when is presented to you in easy to digest form, do not hold, on things you know, you may learn something, no one knows everything.
THE TRUTH IS BORN IN DISCUSSIONS, but constructive discussions.
I am suggesting that you go back and READ, READ AND READ MANY MORE TIMES this thread from page one, and take your time to check all pictures and links. Also read the information, which you have, completely, DO NOT CONFRONT YOURSELF.
So far, you are not being able to prove why synthetic oil should not be better than conventional even if you use MB synthetic oil recommended by them with lower viscosity than Mobil1 or Valvoline.