Thanks tensecondz1 for the compliment!
outrun, oil consumption is a complicated thing because so many factors determine it and volatility is just one of them. I think that the other factors are viscosity, seal swell/shrinkage effects of the oil, polarity of oil (stronger polarity causes oil to seep past seals such as valve seals and "stick" to metal more evenly), and the ring cleanliness the oil provides. There may be others I haven't listed. Of course the engine type/condition, and the operating conditions are factors too but those aren't oil variables.
I'm sure that GC is less volatile than Chevron Supreme so the higher consumption you got with GC must be from one of the other factors. If I had to guess what accounts for that I'd guess it's GC's and M1's effect on your seal dimensions, but I could be wrong. When I used Redline for several oil changes with a 2002 Subaru Impreza RS, it consistently burnt it at twice the rate of Valvoline Synpower and Pennzoil dino oil, and I think it was because of Redline's effect on the seals. I know the Redline has very low volatility so we can rule that factor out. If I were you, I'd try to stick with oils that have the lowest consumption in your engine since burning oil forms ash and varnish in your combustion chambers (no good).
You asked about additive carrier oil vs base oil. In a liquid mixture, the total evaporation rate (volatility) should be the sum of the subcomponent's volatility times their volumetric percentage of the whole. Take Lubromoly 0W-40 as an example, it has 80% PAO and 20% mineral oil additive carrier. Let's assume the PAO is all of same structure and has a NOACK volatility of 5% by itself. And the mineral oil has NOACK volatility of 10%. Then the NOACK volatility of the mixture should be 80%*5 + 20%*10 = 6. So the more volatile component raises the volatility of the mixture but not by much because it's such a small fraction of the whole mixture. Of course as time goes on, the more volatile component is leaving at a faster rate and eventually there is very little of it left so the volatility of the mixture rises. It's like putting gasoline in oil and heating it; the gas will evaporate quickly and eventually it wil be mostly oil left behind.