I am not going to claim to be a fluid expert, but wouldn't a thicker viscosity oil cause faster wear and more noise?
Have you tried a 90w GL5 gear oil (or 80w90 GL5 oil)?

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2021 Charger Scat Pack Widebody "Sinabee"
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1972 280SE 4.5
2014 Jeep Grand Cherokee Limited "Hefe", 1992 Jeep Cherokee Laredo "Jeepy", 2006 Charger R/T "Hemi"
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