Umm, it is 85%-95% Group III, per Amsoil's MSDS sheet:
http://www.north-american-lubricants.com/pdf_file/xl_series.pdf
"Hydrogenated Base Mixture, CAS# 64742547, 85-95%"
So, the 7500 oils are more or less equivalent to Castrol (North American) Syntec, Rotella T Syn, etc.