Rear axle fluid

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pragmatic

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Ford recommends 75W-140 synthetic (never need replacing). Since I'm changing trans fluid (60,000 miles for 5-speeds) thought I might as well do rear. Motorcraft web site does not list a 75W-140 synthetic (only 75W-140 high performance and 75W-90 synthetic also a 75W-90 fuel efficient high performance). Recommended fluid for F150 is also synthetic 75W-140 and this needs to be changed if your towing. So what gives?

Mobil makes a 75W-140 synthetic (at least their web site lists one), but local stores don't have, only 75W-90. On place had Coastal semi synthetic75W-140 and Valvoline full synthetic 75W-140 (but only one quart and I need 1.5 quarts). I know Amsoil makes one but I'm not a fan (if your one of their distributors don't post telling me how it's better than Mobil, I already know that).

Not too worried but what should be used?
 
I would do 75W-140 IMHO.

FWIW I used HydroTex Multi-Film 80W-140 Hy-Diamond Gear Oil. That's a premium industrial brand we use at work.
 
Mummy thread bump.

OM calls for 75W-90.

Amsoil site and 06 shop manual call for 75W-140.


So which is it? 75W-90 or 75W-140?



Edit: Did some research, and apparently Ford now recommends 75W-140 in place of 75W-90 to address noise issues. Hope this helps others in the future.
 
i changed the rear differential fluid today EASY AS PIE

only thing is how to tell if the bolt is tight enough?
 
Torque specs are in the service manual. It's something like 25 lb-ft.
 
Yes I know that this is an old thread, but...

My '04 Lincoln Owner's manual says "Motorcraft SAE 75w-90 Fuel Efficient High Performance Synthetic Rear Axle Lubrication", while my '04 Lincoln Shop Manual says "75w-140 Synthetic Rear Axle Lubrication". I find it very interesting that they do not agree.

Personally I really can't see using 75w-140 gear lube in an open differential of a light duty with a fairly low numerical gear ration with fairly low power application as the Lincoln LS. I highly doubt that the differential fluid temp in the Lincoln LS get to nor stays above 200 degree F for long where a 75w-140 would then be needed. But if that is what Ford wants us to use... Just as a point of reference the Ford Shop manual for the Mustang 5.0L with a Trac Lok 8.8" calls out a Ford spec that translates to a 80w-90 non synthetic gear lube.
 
AFAIK, they changed their minds about the 75W90 sometime between 2004 and 2006. They now specify 75W140. I assume that they discovered that things lasted longer with the 75W140.
 
joegr said:
AFAIK, they changed their minds about the 75W90 sometime between 2004 and 2006. They now specify 75W140. I assume that they discovered that things lasted longer with the 75W140.
Click to expand...

Especially if you never change the fluid. Ford calls out a 150K mile interval for fluid change, unless you have a E or F-450 or larger van or truck which get changed at 50K miles.
 
For what's it's worth, I rock the 75-140 syn. in my LS, as well as the three differentials in my Land Rover.
 
I was thinking of using the 75w-140 synthetic with the LSD upgrade due to the possible higher thermal loading generated by LSD if you work it fairly hard. There really isn't much fluid capacity back there to deal with any higher fluid temps. Its not like a track car that would have a pump and a cooler for the differential fluid.
 
I started the thread, but have not yet done the fluid change (where did ten years go).
 
There was a technical service bulletin for this, as Joe said they did change it up to 75-140 for all models... including pick-ups.
 
Mummy thread bump, part 2.

I have to tackle this in the upcoming week before a road trip. Can someone confirm it's the 75W140. Also, is there some type of plug or bolt in the housing/cover? I've never completed a diff fluid change on a small car before. I would imagine there is some type of plug or bolt and you use one of those cheap hand pumps correct.

Thanks in advance.
 
Amsoil only in differential with FRPP friction modifier.
Ford & Mobil1 fluids on rest of car.
 
pragmatic said:
Ford recommends 75W-140 synthetic (never need replacing). Since I'm changing trans fluid (60,000 miles for 5-speeds) thought I might as well do rear. Motorcraft web site does not list a 75W-140 synthetic (only 75W-140 high performance and 75W-90 synthetic also a 75W-90 fuel efficient high performance). Recommended fluid for F150 is also synthetic 75W-140 and this needs to be changed if your towing. So what gives?

Mobil makes a 75W-140 synthetic (at least their web site lists one), but local stores don't have, only 75W-90. On place had Coastal semi synthetic75W-140 and Valvoline full synthetic 75W-140 (but only one quart and I need 1.5 quarts). I know Amsoil makes one but I'm not a fan (if your one of their distributors don't post telling me how it's better than Mobil, I already know that).

Not too worried but what should be used?
Click to expand...

The only differential fluid for our cars is AMZOIL SEVERE GEAR, & bottle of FRPP Friction Modifier
 
LSD/friction modifier is moot and not necessary... unless you stuffed a clutch type 8.8 "traction-loc" diff in the case. Synthetic 75w140 is all that's needed. Valvoline or Mobil 1 would be best. No "store" brands.
 
Robb15033 said:
The only differential fluid for our cars is AMZOIL SEVERE GEAR, & bottle of FRPP Friction Modifier
Click to expand...
I had my manual LS on jackstands and worked way back to differential. It said 'lifetime fluid do not change' or something similar. So I didn't. Car has 200,000 on it. Did I make a mistake? ...
 
heyjewel said:
I had my manual LS on jackstands and worked way back to differential. It said 'lifetime fluid do not change' or something similar. So I didn't. Car has 200,000 on it. Did I make a mistake? ...
Click to expand...
Most certainly have it serviced. . Amzoil in the differential.
Transmission needs serviced also once 100K miles is reached.
Motorcraft fluid and filter.
 
joegr said:
Filter on a manual?
Click to expand...
Yes, absoulutly.
Invareas like Texas with spot snd go traffic, at least once a year.
Speak to Mustang dyno shop familure yhinh this transmissin snd ask.
So cheap yo stay health.
Differential fluis is criticsl to kerp wheels rotating.
Performance shops will Aziil snd FFRP FRICTION MODIFIER, perfectly quiet gear box.
MOTORCRAFT ON ALL FLUIDS / Parts, filters
 
Robb15033 said:
Yes, absoulutly.
Invareas like Texas with spot snd go traffic, at least once a year.
Speak to Mustang dyno shop familure yhinh this transmissin snd ask.
So cheap yo stay health.
Differential fluis is criticsl to kerp wheels rotating.
Performance shops will Aziil snd FFRP FRICTION MODIFIER, perfectly quiet gear box.
MOTORCRAFT ON ALL FLUIDS / Parts, filters
Click to expand...

Remind me again where exactly is the transmission filter on an LS equipped with a Getrag 5-speed manual transmission.
 
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