回複：That's ture - the recommended service.

Thanks so much for your advice. This is what I got from BMWCA forum:

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15k is generally thought of by most of us as too long. Mike Miller of Tech Talk recommends 7500k oil/filter change when using BMW synthetic. Personally I change mine between 5500 and 6500 but that's just me being more particular.

Mike has a great document that he will email you if you contact him ([e-mail]) that details his "old school" BMW maintenance to include all the fluid changes.
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