Patman, this one is right up your alley. After reading several UOA of both the Tri-syn and the SS from Mobil, I have a theory. From my time reading the tech board on LS1.com, I see where many people that used M1 TS would experience high rates of comsumption. Then they would switch to Synpower, Redline or others and the consumption would drop. Also, we know that the LS1's have a ring blow by issue that GM has corrected. Now for my theory. We have seen here several posts of UOA that show that the 5W-30 M1 TS shears back to 5w-20 after a short time. My theory is that the sheared or lower visc oil resulted in more blow-by the longer that it was in. For me personally, When I switched my '01 Burb over to M1, I went with what GM said and used a 5W-30 TS. No oil consumption until around 2500-3000 miles and then it would eat it until I put a new quart in and then it would hold until 5-6 K with only being down 1/4 qt. When I switched to 10W-30, I never had to add oil during the 5-6 K between oil changes. At that time, I may have been down 1/2 qt. Now looking at the new SS and how it seems to hold its viscosity, I wonder if the oil consumption may be better. I know that SS is still on the low end, but if it does not shear thin, then maybe it will be better at minimizing consumption. I know that a lot of people on LS1 run their cars hard, which may have sped up the shear thinning of the old M1 TS. I just changed my Burb over to 10W-30 SS. I will post my findings. I did not check on LS1, but has anyone said anything about oil consumption rates on the new M1 SS?