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A friend of mine is an engine design engineer for Honda and said they actually do this. I don't know if BMW does as well. Finishes on reciprocating engine parts are very good, probably on the order of 5-20 microinches RMS, but they still don't fit perfectly. A little grit in the several micron range would promote mild wear and actually help fit.
I don't know what the pass-size on the BMW oil filter is, but if it's like
everything else they design, it's very good.
But I think the 15k interval has more to do with lack of thermal breakdown.
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