Zero make up oil, but how much did you drain? I'm wondering if possibly being down near 3 quarts in this 4 quart sump might have contributed to the low TBN and shear. Most older S series engines I've dealt with have oil consumption issues. I'm surprised you had a head gasket failure, usually on the 8 valve motors the head itself cracks. I've got an 02 SL1 now that I picked up for a song due to a cracked head. My 02 is now on the road and I've run about 6k miles on Syn Power and the oil level has hardly moved. I guess Saturn fixed their oil rings at some point. Since this S car does not appear to have any consumption issues, I think I'm going to run Syn Power again for 7.5K and have a UOA done, either that or SSO for 10-12K. In the past, all the S cars that I have owned or serviced used way to much oil to ever make an OA meaningful. Thanks for sharing your report.