funny my 1992 Polo Green has the factory Mobil 1 label on the hood. I do not think my 91 or 90 had the M1 label on the hood. Not doubting you, but might want to recheck that
From my memory old SG and SH were testing in the 1200-1600 range. I would have to pull out old Blackstone papers, somewhere...Yes, no min or max. back then who cared, you had enough to not worry about it.
SG - SG/CD - SG/CC - SG/SF/CC all approved for LT5