I'm not really arguing the point of 7,500 miles, personally I wouldn't go that long unless I was driving all highway and running synthetic.
But as far as viscosity goes, as I understand it you have to get the oil pretty thin before shear comes into play. I stand by 220 being an ideal operating temperature and viscosity for 5W30 and 5W40 oil. I'm happy to be proven wrong by any oil experts out there.
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