It hasn't been done yet to either of my cars so this is next on my to do list. Both cars call for 75w-140 and normally I'd just go with what a car calls for, but I can't help but think it's overkill. Wouldn't 75w-90 be better for my application? Both cars are open diffs, weigh less than 4k pounds, never tow, and technically say it's a lifetime fill(of course none of us believe this).
Differential service
- Thread starter Torrid
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Originally Posted By: Torrid
It hasn't been done yet to either of my cars so this is next on my to do list. Both cars call for 75w-140 and normally I'd just go with what a car calls for, but I can't help but think it's overkill. Wouldn't 75w-90 be better for my application? Both cars are open diffs, weigh less than 4k pounds, never tow, and technically say it's a lifetime fill(of course none of us believe this).
It usually doesn't hurt to run thicker fluid, but I wouldn't ever step down to a thinner fluid. Your car might be light, but the differential may not be very big or hold much fluid thus needing the heavier weight.
It hasn't been done yet to either of my cars so this is next on my to do list. Both cars call for 75w-140 and normally I'd just go with what a car calls for, but I can't help but think it's overkill. Wouldn't 75w-90 be better for my application? Both cars are open diffs, weigh less than 4k pounds, never tow, and technically say it's a lifetime fill(of course none of us believe this).
It usually doesn't hurt to run thicker fluid, but I wouldn't ever step down to a thinner fluid. Your car might be light, but the differential may not be very big or hold much fluid thus needing the heavier weight.
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Many times eighteen wheelers call for 75w90 gear oil, but they also hold like 5 gallons in the axle and spin slower.
Ford rear ends need it. Some were spec'd lighter and after failers they bumped it to the thick stuff. My old 2004 IRS Explorer 4.6 had the diff gears replaced under warranty and they carved 75w140 on the housing. Went 150k after that until we sold it.
I may go thinner on engine oil in Las Vegas winter, but thinner differential is not a good idea because you have it in service for several years, and summer in LV is too hot for 75W90.
I would stick with the right weight in this application. I'm usually quick to defend otherwise in most cases, but not this one
Agree with others. They spec'd it for a reason. They are both IRS units right? Those hold very little oil.
Originally Posted By: RedOakRanch
Ford rear ends need it. Some were spec'd lighter and after failers they bumped it to the thick stuff. My old 2004 IRS Explorer 4.6 had the diff gears replaced under warranty and they carved 75w140 on the housing. Went 150k after that until we sold it.
+1
Differentials sort of never fail ..... with adequate op viscosity or a grade thicker gear oil.
But it does whine and eventually fail .... with inadequate viscosity and thinner oils.
Ford rear ends need it. Some were spec'd lighter and after failers they bumped it to the thick stuff. My old 2004 IRS Explorer 4.6 had the diff gears replaced under warranty and they carved 75w140 on the housing. Went 150k after that until we sold it.
+1
Differentials sort of never fail ..... with adequate op viscosity or a grade thicker gear oil.
But it does whine and eventually fail .... with inadequate viscosity and thinner oils.
Only two times I had problems with Ford rear ends.
1. Impact damage bent an axle tube causing bearing and seal failure.
2. Ran 75w90 synthetic in place of 75w140. Had both wheel bearing fail with axle damage. No carrier, gear or inner bearing damage. Weird.
1. Impact damage bent an axle tube causing bearing and seal failure.
2. Ran 75w90 synthetic in place of 75w140. Had both wheel bearing fail with axle damage. No carrier, gear or inner bearing damage. Weird.
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The cost difference between Amsoil 75W-90 and 75W-140 is less than $2.00 and since 75W-140 was specified, I would not lower the viscosity without some data to back up that decision. If it were mine, I would install Amsoil Severe Gear in 75W-140 and keep rolling.
Originally Posted By: zeng
Differentials sort of never fail ..... with adequate op viscosity or a grade thicker gear oil.
But it does whine and eventually fail .... with inadequate viscosity and thinner oils.
I beg to differ, I sell plenty of bearings, ring and pinion sets, and center sections. Use the right fluid.
Differentials sort of never fail ..... with adequate op viscosity or a grade thicker gear oil.
But it does whine and eventually fail .... with inadequate viscosity and thinner oils.
I beg to differ, I sell plenty of bearings, ring and pinion sets, and center sections. Use the right fluid.
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