Originally Posted by attila
Here is the story: I track the car relatively often (4 track days in May only one in June but 4 coming up in July)
So I like to change the engine oil more often than BMW recommends. After the 1,200 mile service I changed it at 4,200 miles and now at 8,000 miles I went in for another oil change. And here is the thing, the SA was telling me that based upon the "key reading" my car needs an oil change (just after 4000miles), so they did it free of charge?? I am not complaining but somehow worried that the oil could have been deteriorated so much that the car needed a change?!!
What is the car actually measuring in the oil? How is it determined by the ECU that the car needs an oil change? By the way no service light came on, nothing was indicating that something maybe not right.
CBS, or Condition Based Service, determines when your car needs use-driven service like oil changes. My understanding is that CBS factors in things like engine time, engine speeds, and fuel consumed, likely as a bias off of a normal 15k mile cycle. So "heavy" use could drive down the cycle but remember that CBS doesn't know about your 4,200 mile change (you did it yourself or the dealer didn't reset CBS as you would have paid for the early service), it is comparing 8,000 miles with the last known service reset of 1,200 miles. It thinks 6,800 miles have gone by. The car doesn't measure anything in the oil.
2015 BMW M5 Sedan M-DCT w/Competition Pkg and Carbon Ceramic Brakes, Driver's Assistance, and Executive Pkgs, B&O, Alpine White / Sakhir Orange and Black Full Leather, lots of carbon fiber, and a Trunk Monkey called "Der Stig".