Generally yes, trust the olm. The GM system has been discussed here many times and it is generally agreed upon that it works well, and a sure bit better then mileage based in most scenarios.
In a nutshell the olm will know how many times the engine turned over, how hard you were on the engine, if the engine was cold or warm or hot when you were hard on it, the idle time, the sustained engine temp, and how long it has been.
It does NOT know however if you used cheap oil or the best oil ever.
If you are under warranty always follow the olm, regardless of what oil you use. I believe you always have to use a dexos oil on that car too. Otherwise if you use the bare minimum, maybe change it at 20% life remaining, if you use a super premium best of the best oil, then maybe 3%. If you want to be extra special to the engine, change it at 50%. And if you are out of warranty and want to run the oil as far as you can then reset it and run it down a second time, changing at 50% or whatever your analysis shows is best.