75w-90 Specs

[ka9mnx]

Did the specs change for 75w-90? If so when? My Ford trucks are spec'd for 75w-90 but, I think, Ford now uses 75w-140. I cannot find a TSB that points to the change and that would be helpful. When I bought the Ranger it came with 75w-90. A year later when they rebuilt the rear axle they put in 75w-140 (as per the invoice).

Any information would be greatly appreciated!

 

[zeng]

At what mileage the rear axle requires rebuilt, and why is that so ?
There are axles that works for 20-30 years and running.

 

[Oildudeny]

when I had my 98 f-150 there was a steel service tag bolted on the differential cover that stated 75-140. my truck had the 3.55 lsd rear

 

[IndyFan]

A tow package or hitch package is usually the difference, with 75w90 or 80w90 being adequate if not towing or hauling heavy loads.

 

[Rollins]

It was revised in 2005.

http://www.ptplab.net/upfile/201402/13/094319180.pdf


revision years


1998 revision


2005 revision

Interesting what the OEM fluid visc. might have been...probably closer to the old upper limit of 24cSt...

 

[Snagglefoot]

I use 75w-90 because of the freezing winter temps but in South Carolina 75w-140 should be fine. Also, folks up here run 75w-140 a lot even though the videos with plexiglass rear covers show the lube looks like jello at real low temps.

 

[zeng]

Originally Posted by Rollins
It was revised in 2005.

http://www.ptplab.net/upfile/201402/13/094319180.pdf


revision years


1998 revision


2005 revision

Interesting what the OEM fluid visc. might have been...probably closer to the old upper limit of 24cSt...

Oops, I had been wrong in referencing date of addition of new SAE 110 and SAE 190 gear oil viscosities grades as July 1998 , when it was actually June/Jan 2005.

 

[ka9mnx]

Originally Posted by zeng
At what mileage the rear axle requires rebuilt, and why is that so ?
There are axles that works for 20-30 years and running.

I drove it off the lot, new, knowing it had a ring gear bearing problem. I had to make a trip to Texas on business. When I got back I took it directly to Ford for warranty repair. It had about 3k miles on it. They replaced the ring, pinion and spider gears and all bearings/seals.

 

[ka9mnx]

Originally Posted by Oildudeny
when I had my 98 f-150 there was a steel service tag bolted on the differential cover that stated 75-140. my truck had the 3.55 lsd rear

My 93 F150 owners manual says 75w-80.

 

[ka9mnx]

Originally Posted by IndyFan
A tow package or hitch package is usually the difference, with 75w90 or 80w90 being adequate if not towing or hauling heavy loads.

The Ranger has the towing package including trans cooler. Owners manual says 75w-80.

 

[Astro14]

My 2000 Ford Expedition specified 75W140 for the rear differential.

It was equipped with the 5.4 engine, 3.55 gears and tow package.

I used 75W140 synthetic in that rear end with no issues. Including -30 weather in Vermont winters and towing a 7,500# car/trailer combination.

 

[ka9mnx]

Thanks zeng! The SAE paper explains it all...

 

[ka9mnx]

Thanks to everyone for their time and comments!

 

[zeng]

Originally Posted by ka9mnx
The SAE paper explains it all...

Basing on Rollins' SAE paper above, I would interprete modern day 75W140 of KV40C 175 cSt as equivalent to 2005's specified '90 wt' , setting aside 75W90 of the era being a 100 cSt KV40C.

 

[CT8]

Both my Fords recommend 75W-85 in the rear diffs. One already has Syn 75W-140 the other one will soon have. Syn 75W-140. My 96 Toyota had syn 75W-140 in the rear diff.