I did my first change at 2K, but would have performed it earlier if I had not been on the road. However, I also know engines, and know the GM oil life system. I have personally checked it out on my previous GM vehicles, and through an oil analysis by an independent lab, the oil life system is quite accurate. If anything, it sways to the side of safety, and the oil analysis shows the oil's TBN is higher than should be at the percentage of oil life remaining.
It must be understood that the system's algorithms are based upon a specific grade of oil as specified by GM, and not using oil that meets this specification will cause the oil life indicator system to be inaccurate. (A better grade that meets the oil specification such as Mobil 1 is ok.) In addition, it cannot take into account extra dirt into the system, it has to assume you are using the specified type of air filter, and the intake system is sealed as from the factory. So, if you open up the air intake system, switch to a filter that is not as efficient for particle filtering, then the oil life system may not be as accurate.
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Black Sheep Hummer Squadron
(ME TOO)
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