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      05-08-2009, 02:43 PM   #43
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Drives: 335i
Join Date: Feb 2009
Location: usa

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Originally Posted by markinva View Post
please tell me what this

Originally Posted by carve
Go ahead and change your oil on your own and then tell me if the computer lengthens the time until it says you're due for your next change (hint: it doesn't!)

has to do with this:

Originally Posted by carve
Reread my post. My point is, it's all based on the algorithm unless the sensor detects a LOT of conductive contamination in the oil. This would include metals and maybe water with dissolved ions, but it wouldn't include anything about silica (dust) or anything about the lubricity or viscosity of the oil. Many people, I think, are under the impression that the sensor is like an oil analysis lab in their engine.

They call it "condition based service". However, they just PREDICT what the condition SHOULD be for the most part- otherwise when you put in fresh oil it would recognize it as....fresh oil. This demonstrates that the sensor is just there as a sort of last resort safety factor in case the prediction completely screws up (e.g., your engine start shedding copious amounts of metal or you blow a head gasket or something). Nice to have since there is no dipstick to examine the oil manually, but nothing actually MEASURES the condition of the oil to any degree of accuracy beyond "probably OK" and "totally screwed".

Furthermore, their recommended change intervals are what they predict are needed to allow the engine to last for a particular amount of time. We have NO IDEA what their target is, nor their degree of certainty/safety factor used to hit that target. If someone knows I'd LOVE to hear it.