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      11-27-2007, 01:00 PM   #19
larryn
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Drives: '97 332ti, '21 X5 45e, '16 GT4
Join Date: May 2005
Location: Seattle

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By the way, to further bolster the arguement for changing oil more frequently, because of the higher than normal temps and oil pressure of the N54, it degrades the oil at a much quicker rate than a NA motor.

Take a look at the results of a Dyson test (similar to Blackstone), where you can see fairly major degradation due to unburned fuel in the oil (common at minimal levels). This makes it not as effective as a lubrican't, and causes premature engine wear, as seen by the increased contiminants in that test (Boron is 1.6x the "warning" level, but there are other issues with that sample).

There is a fairly extensive thread about this at e90post.com. It's a detailed discussion about this exact engine, including test results from multiple sources. They all heavily point to the N54 needing more frequent oil changes than the 15k mile covered intervals.

Btw, oil dilution and degradation is directly effected by how you drive your car. Factors like how many short trips, not letting it get up to temp before stomping on it, high stress driving(track/autox).. will all contribute to oil degradation/contamination.
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