Question about Viscosity Index

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434
Location
MD
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.
 
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4,942
Location
Billings, MT
From what I've read, you can't compare the viscosity index of one weight of oil against another. And I believe that the minimum VI numbers are without any additives. No pour point depressants, no viscosity index improvers, no friction modifiers.
 
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