Isn't science fun! We have some research papers indicating that increased soot loading increases wear rates in diesel oils, and we have other research papers indicating that wear rates decrease the older the oil is (in gassers). So in review... don't change your oil frequently, and don't change your oil infrequently.

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1968 220D, w115, /8, OM615, Automatic transmission.
My 1987 300TD wagon was sold and my 2003 W210 E320 wagon was totaled (sheds tear).