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Old 10-08-2008, 11:22 PM   #30 (permalink)
trebuchet03
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Join Date: Dec 2007
Location: Bay Area
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The Miata - '01 Mazda MX-5 Miata
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Quote:
Originally Posted by flydude1221 View Post
I wonder how the GM oil change monitor system decides when to tell you it is time to change? Maybe they just detect the pressure and temp to a given table of values ?
Not entirely sure how GM does it - a friend once explained to me that it's based on starts/stops, miles, etc. etc. and thrown into an algorithm. If that's the case, you'll probably have to trust that GM got it right AND that they're not short selling you (outside of a reasonable safety factor).

But BMW, from whatever article it was that I read, uses "electrical properties" (resistance?) of oil which change as the oil wears out.

Not sure how effective it is....
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