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Forerunner:
You are recirculating dirty oil into the filter, and then filtered oil into the engine. If the filter isn't is bypass, and hasn't collapsed, then the filtered oil is meeting the cleanliness spec IMO. Your logic on the engine using dirty oil is applicable to a vehicle without a full-flow filter. Not true of modern automotive engines.
The published oil filter change interval is 15,000 miles, but it does vary with driving conditions. Yes, the BMW spec speaks to oil filters.
Not an expert here, but the E34 535 likely holds 7 quarts, was designed to use non-synthetic oil, and probably had a 7000 mile oil change interval. The filter change interval was specified because the filter held a quart of dirty oil, not because it was necessarily worn out. Some conjecture here. Those who doubled the oil change interval and ran them to 12,000 to 15,000 miles on synthetic oil would suggest that the filter is good for more than the spec mileage.
These vehicles run a lot cleaner than an E34. The best indicator of that is the tailpipe emissions. Compare the specs, and see that the engine simply isn't producing as much crap as the older models. Less to contaminate the oil. As long as you are using an OEM filter (some similar-looking filters pass larger particles than the OEM filter), you are safe with 15,000 miles on a filter. You may want to change your oil earlier, and there are reasons for doing that, but the filter isn't the limiting factor. Engineering analysis shows that, as most owners use the lights, and the lights tell them to go in at 15,000 miles. There will be a normal distribution of failure points, so it it was designed for a maximum of 15,000 miles then a portion would fail early. Hasn't happened.
If you want to do it early, that is great. I was only suggesting that taking it from 15,000 miles down to 12,000 miles would be prudent; taking it down to 7500 miles is convenient given the 15,000 mile changes that BMW pays for, and taking it down to 3,000 may just be wasteful of our earth's limited resources. Still, it is your call.
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2007 X3 3.0si, 6 MT, Premium, White
Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue
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