kobeck, your plan is AOK. You don't really want to do analysis on the first change (maybe two) after switching a car that has been on dino for years, because it will flush out some old buildup. That could skew the analysis results. At the second or third change the data should be good. Assuming you analyze at 5k and there are no abnormalities, you generally base your interval on the soot percentage, figuring 2% as the general limit. So if the analysis shows 1% soot at 5kmi, you can estimate that a good interval is ~10kmi, when the engine should kit ~2%. Disable the EGR if you haven't already, btw.
DA, I understand what you're saying about our older cars being harder on oil, but don't completely agree.
I also don't have hard data to refute the notion so the following is my opinion. The newer diesels produce less soot, so they can safely use the relatively high FSS interval. Hence the MB FSS upper limit near 20kmi (!) where many of our older MB's probably shouldn't be going past 10-15k. Gassers are a totally different story, they can often go 20k+ (all this is assuming non-severe service). I do think 616/617 are harder on oil than 601/602/603, which in turn may be a little rougher than the new 606 engine. Anyhoo, IMO it's a good idea to do at least one analysis on your engine so you have a rough idea of what's happening inside...
