I'm a fan of long drain intervals for some vehicles, but my understanding from Used Oil Analysis (UOA) of the 616/617 engines (240d/300d...the old guys) was that they soot loaded the oil too much and you had to run a factory (3k-4k) drain interval.

I'm happy to hear 75S is running 1k with clear oil...but also shocked, my 240d runs relatively clean (smokes only on real hard throttle) but I get dirty oil right after a change.

The 601/2/3's and especially the 606 are a different story and are the ones where you can do a longer OCI because you're not fighting soot.

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05 E320 CDI
99 SL500
02 530i

82 240D SOLD
83 240D Euro 4spd SOLD
86 300D Euro Auto SOLD