Differential fluid change - do I need friction modifier?

[Ruger]

...for vintage geezers like me and Ruger.

Patience grasshoppa, you get there some day.

 

[Nick@Apollo-Optics]

I'm holding off on my AFE diff cover until we have some conclusive info.

 

[badmonkey]

My interpretation of this is, you do not need to add friction modifier to the rear, as it is not a LSD. If a modifier is already added to the oil, it is not going to hurt anything, as long as the oil is the right type/spec.

 

[155mm]

So if the 2014 manual calls for 75w-85 for the rear, why is everyone using 75w-140?

 

[Chris@FreedomMotorsports]

The 140 offers better protection for the gears in vehicles that see a lot of offroading...

 

[Madcowranch]

So if the 2014 manual calls for 75w-85 for the rear, why is everyone using 75w-140?

It doesn't. It calls for 75w-140.

---------- Post added at 12:16 PM ---------- Previous post was at 12

http://www.fordservicecontent.com/F...0-Owner-Manual-version-2_OM_EN-US_01_2014.pdf

---------- Post added at 12:18 PM ---------- Previous post was at 12:16 PM ----------

Look under cap's and spec's

 

[155mm]

It doesn't. It calls for 75w-140.

---------- Post added at 12:16 PM ---------- Previous post was at 12

http://www.fordservicecontent.com/F...0-Owner-Manual-version-2_OM_EN-US_01_2014.pdf

---------- Post added at 12:18 PM ---------- Previous post was at 12:16 PM ----------

Look under cap's and spec's

I saw that, but the Raptor supplement shows something different than the main F-150 manual. If it's better protection for offroading, why did they spec it differently? Typo?

http://www.fordservicecontent.com/Ford_Content/Catalog/owner_information/2014-F-150-SVT-Raptor-Supplement-First-Print_rp_en-us_09_2013.pdf

 

[Madcowranch]

Changed my diff fluid and purge valve the other day. Fluid was dark but no water contamination. Was surprised with the water crossings I've done. Is there some kind of check valve in the breather?

 

[Rakimb17]

I swapped out to an AFE different cover yesterday and i think fluid is a little low. I put in two bottles of friction modifier thinking that i was still going to get 4 quarts of diff oil in. I only got 2.5 quarts in before the sight glass filled up. So I'm full with only about 3 quarts of fluids. Wtf?


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[Yukon Joe]

Changed my diff fluid and purge valve the other day. Fluid was dark but no water contamination. Was surprised with the water crossings I've done. Is there some kind of check valve in the breather?

I didn't think there was. It is routed up to the bed cross frame rail. It typically doesn't get water in there, although I have.

What was the summary / conclusion on the friction modifier?

Yukon Joe
www.RUNRAPTORRUN.com