The C* is a constant that varies depending on the durability of the oil used. I typically recommend these C* values:
Average quality, API/SM petroleum oil, C* = 50
Average (7-9 tbn), Group III synthetic, C*= 90
Top Tier (10-12 tbn), PAO/Ester synthetic, C* = 125
The Amsoil 0w-30/SSO may...