I think there's a difference between Magnesium Carboxylates and the newer Overbased Magnesium Sulphonates when it comes to build up under the ring pack in diesel engines .
It's the hard particle build up doing the abrasive damage while being swiped up and down the cylinder by the piston ring , not the magnesium in solution .
Moisture in the crankcase is a major cause of this from what I read .
MG ,
New oil analysis is one way to tell which oils use magnesium obviously but these metals are proprietory and the types of cannot be distinguished . Labs can have trouble reading levels of certain calciums vs magnesium even .
The days of oils using lots of magnesium may be numbered but many companies still use it in their oil formulas for both gas and diesel engines . The 506 oils will have it at around 300ppm , Amsoil uses it at around 500-600ppm .
Mobil Trysyn used it at almost 1000ppm . I no fear magnesium
Many are trending towards Overbased Calcium but I read that high Zinc competes with it for a place on the metal .
Nothings going to be easy for the chemists of 2010
Sulfur is another component the makers are taking out of formulated oils . One step towards this is using higher refined base oils and I read that the days of Sulfurized MoDTC is numbered because of it .
Moly on the way out , esters and components of are paving their way in