How can Motorcraft Blend 5w30 have an viscosity index of 163 while Pennzoil Platinum 10w30 has a lower index of 154? Furthermore, the MC 5w20 has an index of 164 which is higher than the MC 5w30. What am I not understanding? I thought synthetic group III had to exceed the 120 mark. Thanks guys, I just want to know how to interpret the MSDS's.