MTF Comparisons?

S'cuder said

If you try blending, I would use this, a straight 140 GL-4. Just an educated guess, but I think it's closer in composition than most other gear lubes. You might lose some of the shifting qualities you have with straight synchromesh, but it's a lot heavier than 75W-140. That'll give you a better chance of quieting down your trans.

CRC SL24228 Gear Oil + Cross Reference | FinditParts

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I agree.
However, 75W-140 GL4 is the same as straight 140 GL4 when it's warmed up.
The viscosity changes as it's warmed up to full operating temperature.
The ''W'' in any oil is for winter, not weight.
And using GL4 oil is the right choice, not GL5 which is too slippery.
So, the oil flows like 75 weight oil when cold and changes to 140 when fully warmed up.
I think that this would be a better choice if it were me, but straight 140 would do the trick too, I'm splitting hairs here...