From George...
"If you find you are using synthetic oils as a replacement for your previous mineral-based oils, dont be surprised to find different scavenging results. (Synthetic oils often appear cleaner because they cant dissolve contaminants and keep them in suspension for the filter to remove. Those contaminants are often found as sludge in the bottom of sumps and passages in many engines.). My point is to be certain that, if you are comparing oils, its important to make ALL the comparisons.... comparable.)"
I have to say Hmmmmmm
Was at my dealer today and my open station M9 is there getting some R&R and the overhead run. Dennis took the valve cover off while I was standing there and at 4000 meter hours and a steady diet of synthetic (Rotella) diesel oil, the overhead is as clean as when it was new. So no I was pleasantly surprised at the absence of sludge or blowby for that matter. Me thinks she will go 10K hours with no issue.
I was really expecting some but there wasn't any. Like I said, my oil never gets dark between changes, dark brown but never black. In fact none of my diesels turn the oil black. All get fed Rotella T5.