Patman,
Even if the GC, 0w30 had a pour point of -81F, I'm not sure you could conclude what type of basestock blend it was. When Amsoil released their Series 2000, 0w30 back in 1995, it had a pour point of -76F and it was primarily a PAO based oil. I remember this very well - I thought it was pretty impressive on paper but not particularly useful unless you lived in the Arctic.
The GC, 0w30 seems to be pretty comparable to Mobil 1, based on the limited data I've seen. The real proof of the pudding would be to run some 10k-12k drain intervals and see if it holds up as well as Mobil 1 and Amsoil. Any ACEA A3/B4 rated synthetic should last for at least 10,000 miles when used in a clean running engine ....
Ted