this a question I've been meaning to ask. Sort of in reference to the other thread here about which automaker will be next. My father-in-law has a chrysler 300C on order, with the 5.7L hemi, and as was stated the engine calls for 5w-20 oil. Is this motor any different from the 5.7L hemi of the past year or two? And didn't the previous 5.7L's call for 5w-30? Didn't the dodge hemi hit the market before the 5w-20 revolution? Not to mention a few engines by ford, maybe the v-8's in the trucks if I remember correctly, which always ran on 30 weight. If that's the case, then doesn't this prove that the move to 5w-20 isn't based on the engine (since the design hasn't changed) and more to do with EPA/CAFE/fuel economy?