What oil for a Ford with a Sterling rear axle?

[Chris142]

This is on my New to me 87 F250. The owners manual does not give weights...Just a Ford part number.

 

[Jim_Truett]

The 10.25" rear diff in '87 used 75w-90 synthetic according to my records.

 

[Bgallagher]

How does the fluid look? You might want to run it for a short period with cheap Dino to flush it out before you go synthetic.

 

[RamFan]

Originally Posted By: Chris142
This is on my New to me 87 F250. The owners manual does not give weights...Just a Ford part number.


Just out of curiosity, which engine?

I had an '88 F250 XLT Lariat with the 7.5l V8 in it as my first vehicle. I miss it, wish I could buy it back and restore just so I could keep my first vehicle.

 

[Chris142]

6.9 diesel with a 4 speed stickshift

 

[Roadkingnc]

75w140 synthetic

 

[Jim Allen]

Depends how it's used. Tow a lot, tow heavy,tow in hot weather, use a 140. A 75W140 syn is best because it will deliver the last loss sue to viscosity .Otherwise a good 90 grade is fine and saves you a little mpg. I have all the manuals for my '86, and here is what it calls out: Ford Spec ESA-M2C154-A , which was a 80W90 oil (-15F-100F). They called for a 85W140 in ambient temps +15F- over 100. Syn gear oils were virtually unknown then, so you can translate. FWIW, I run a 90 grade in my truck (the LE607 in the story below)

For To the Point info, go here: Diff Oil Temps

 

[Rob_Roy]

My 10.25" pulls heavy loads in the summer, and plows snow on the winter. Amsoil 75w140 works great for me.

 

[Chris142]

I don't normally tow anything. Just going to use the truck to haul Prospecting equipment and maybe a quad out into the desert.

 

[OVERKILL]

The AMSOIL gear lube in 75w140 is a solid choice.

 

[buck91]

Looking to refresh the rear did oil on my 99 f250. Same rear end manual specs 75w140 synthetic ... seems the jury is out on whether going to lighter 75w90 in a low/no towing situation is alright??