I have read that the parameters on GM's Oil Life Monitor is 1 year or 7500 miles for oil changes...that doesn't seem to be the case if your numbers are correct...
Here's is what the OLM in this vehicle has been telling me for the last 5+ yrs.
If you ask me the previous owner(s) should have divided the miles by 2 to arrive at these percentages, or just go no longer that 50%.
Until recently I increased the oil sump capacity to 11 qts.
140,700, OLM 25% w/8,100 miles on Mobil Delvac 1 ESP 5w-40
148,600, OLM 35% w/7,800 miles on Mobil Delvac 1 ESP 5w-40
157,200, OLM 25% w/8,600 miles on Mobil Delvac 1 ESP 5w-30
167,400, OLM=13% w/10,200 miles on Mobil Delvac 1 ESP 5w-30
174,200, OLM=31% w/6750 miles on Kirkland 5w-30
182,800, OLM=??% w/8600 miles on Amsoil Signature 0w-20
190,400, OLM=39% w/7,600 miles on HPLoil.com 0w-20