75W-140 rear diff/75w-90 front diff?

[93explorereb]

So 75w-90 synthetic gear oil will be too thin for the rear diff? I was thinking of using it in both diffs, however, I keep reading posts of how 75w-140 should be used in the rear diff only? What say you? 93 explorer eb 4.0 4wd, 4 dr 165,000 original miles. 1997 explorer 5.0 awd 4 dr xlt 123,000 original miles. Thanks in advance!

 

[Runnin'OnEmpty]

So 75w-90 synthetic gear oil will be too thin for the rear diff? I was thinking of using it in both diffs, however, I keep reading posts of how 75w-140 should be used in the rear diff only? What say you? 93 explorer eb 4.0 4wd, 4 dr 165,000 original miles. 1997 explorer 5.0 awd 4 dr xlt 123,000 original miles. Thanks in advance!

Ford recommends 75w-140 synthetic in the rear diff with the later
models. You can't go wrong with that. (That's what I use in all my
vehicles).

You can use either weight in the front diff, the reason being the front
takes only 35-40% of the total torque developed. Therefore the 75w-90
will work fine there. The only disadvantage to using the heavier oil is
a (very slightly) lower mpg because of the drag of the heavier oil.

 

[93explorereb]

Ford recommends 75w-140 synthetic in the rear diff with the later
models. You can't go wrong with that. (That's what I use in all my
vehicles).

You can use either weight in the front diff, the reason being the front
takes only 35-40% of the total torque developed. Therefore the 75w-90
will work fine there. The only disadvantage to using the heavier oil is
a (very slightly) lower mpg because of the drag of the heavier oil.

Thanks! I will be doing both trucks this coming weekend, and I am trying to get this stuff done before the winter.