The one major difference, is that the zone classic is asymmetric and the AI is symmetric.....So the drilling differences are obvious there. But otherwise, the AI has activator Plus, which is slightly stronger than regular. The AI will "want" to be slightly earlier/smoother than the classic due to core design as well. The AI *should* be able to handle some more oil in box (rough buff as compared to high gloss, as well) with the stronger cover, but it's not a heavy oiler.
Hope that helps some. But the main difference in a decision is if you want asymmetric or symmetric.
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- Andy
Brunswick...........'nuff said.