The spec is 5.6 liters on engine oil. So if you add 6 qts of oil, you will be just a bit over on the stick. Also remember if no one has say it before. Remove the filter first and leave it out and then change the oil and then put the new filter in. That's because the filter will maintain at least 1/2 qt of oil.

 

Update, my wife took her GC back to the dealer for an oil change and again the level was extremely high afterwards. Complained and the dealer drained out some oil. Incidentally my mother also bought a GC (a 2013 bought new), which had normal oil level until the first oil change, after which the oil level was also very high. (done at a different dealership). Not sure what the problem is, the 3.6 has been out for a few years now and hopefully the 'factory trained technicians' would have caught on by now.