You have it backwards. I went from Dino (10x40 & 20x50 mixed) to Amsoil 20x50 zmax when I got the immediate drop in PSI, especially when warmed up.
I actually had anther thread on this subject here:
http://forums.maxperformanceinc.com/...count=48<br />
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Adam
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1964 LeGTO
469, M21, 3.42
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