Blowby is nothing to worry about. My engine has had a good amount of it since I bought the car....6 years and 75,000 miles ago....and it still starts fine in the extreme cold. Just keep on maintaining and enjoying it....proper oil change intervals with a good oil will minimize the increase of blowby and timing chain wear.

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
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'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)