While it isn't the manufacturer's data, a lot of times to get a ballpark of what I need for fluid, I look on the Amsoil site.
Heres what they say. I do not know anything about the Hypoid HGO-1 fluid, if its a regular gear oil or what. I'm sure others will chime in on some better details. But 75w85 is what Toyota does spec, but a 75W-90 would be fine.
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