I am quite certain that if there is an oil quality sensor it is something simple like conductivity, not an actual measure of lubricity, and no sesnor in the oil pan is going to sense sludge buildup. This means it can only measure really bad oil (or lack of it), and all the other "data" is run time, temp, cold starts, etc matched to expected oil life. Needless to say, it isn't possible to enter the oil grade or supplier info.....
Many owner experienced severe sludge problems, the MLs were the worst for some reason, if they used dino oil, even the better brands, and changed by the FSS indicator. My friend the MB mechanic has been warning his customers to use synthetic based on his observation of the condition engine when the oil was changed. One customer did ruin the engine, but got it replaced, I think.
I'd ignore the FSS and use synthetic oil, changed (with filter change) at 6000-7500 miles unless oil analysis is done. If you do oil analysis, change as indicated (or sooner!). Oil is cheap compared to a new engine, and even a lousy design will run forever if cared for -- our 1990 Chevy box van now has 300,000 miles with no engine work at all except for tuneups, serviced at JiffyLube since new!
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!