2010 Ford FX4 Front & Rear Differential Fluid

[CarbonSteel]

I just changed the front and rear differential, transfer case, and transmission fluids. I will be sending the samples to Blackstone for UOAs next week (Houston is covered in ice today). Mileage on all fluids is 13,300.

All of the fluids were the OEM fills which were (from front to rear of truck):

• Motorcraft 80w-90w Premium Gear Lube
  
• Motorcraft Mercon LV Transmission Fluid
  
• Motorcraft Mercon 5 Transmission Fluid (XL-12)
  
• Motorcraft 75w-140w Synthetic Gear Lube

The transmission fluid was really dark (but I hear this is normal on the 6R80 transmission) so I am not too concerned about it and the transfer case fluid. I replaced both with OEM Motorcraft fluids.

What did seem strange was the color of the front and rear differential fluid (of course I understand color is not a science of any type). The front fluid (8.8 Ford axle) was a creamy honey color (as if there was water in the oil--truck has not been in water other than rain). It still smelled like gear oil, but I have never seen oil with only 13,300 miles have this color. I replaced it with Castrol Syntec 75w-90w which had a very clear color and not milky in the slightest. Anyone see MC 80w-90 straight from the bottle? Is it close to this color? Here is the front fluid:




Next, the rear fluid seems to have a large amount of metal in it. I have changed the rear fluid in almost every truck that I have owned at about 10-13,000 miles and none of them were this gray. When looking at the oil against a white background, one can almost see the metal filings in it. Anyone else have this experience with the 9.75 Ford axle? Is this normal? I put MC 75w-140 synthetic back in it, but I plan to replace with M1 in front and rear at the next fluid change. Here is the rear fluid:





Thoughts and comments are welcome! I will post the UOAs when they return from Blackstone.

 

[190E26FTW]

Wow that is interesting. I too have never seen a honey colored fluid before. Thanks for posting. Hopefully some other guys with more knowledge about this can jump in.

 

[Cup of Joe]

I do believe its the color of the lube going in. I changed the gear oil in my 2011 ranger at 3k miles and it was far greener then your front diff fluid.

Motorcraft 75w-90 lists color as yellow to brown. The additives in the 80w-90 and 80w-140 are different. If I can find that data again I will share it.

 

[OVERKILL]

The Shaeffers gear lube is grey just like your rear diff fluid FWIW.

 

[CarbonSteel]

Originally Posted By: OVERK1LL
The Shaeffers gear lube is grey just like your rear diff fluid FWIW.

My fears may be misplaced then--since I did not see the virgin oil for the front or the rear, this could be the normal color of the oil (but there seems to be a lot of metal in the rear oil). Perhaps, someone has seen the virgin oil...

 

[OVERKILL]

http://www.bobistheoilguy.com/gearoiltest.htm

There is another one too, but I can't find it. Compares Shaeffers to Lucas.

 

[kcfx4]

im wondering why you changed it? that soon

 

[Ben99GT]

The last time I changed the front diff fluid in a '05 F150 4x4, the front diff fluid looked exactly like your pics.

At the time I assumed it was contaminated with water, now I'm not so sure.

 

[unDummy]

Its good to do a early change out to remove the break-in debris.
There are actually differentials that used to require it.

 

[CarbonSteel]

Originally Posted By: kcfx4
im wondering why you changed it? that soon

To remove the break-in metal and contaminants. The rear differential had a lot of metal on the magnetic plug and on the magnet inside the differential. These parts are no different than the engine when it comes to break-in and my engine UOAs show that early and often changes remove the metal that is created as the parts wear-in. I fully expect each UOA to show high amounts of various metals from wear-in.

 

[CarbonSteel]

Originally Posted By: Ben99GT
The last time I changed the front diff fluid in a '05 F150 4x4, the front diff fluid looked exactly like your pics. At the time I assumed it was contaminated with water, now I'm not so sure.

I thought the same...like what the...??? It may be the formulation of the oil from MC that causes the oil to appear that way. I should have the UOA results within a week or so.

 

[Jim Allen]

The diff oil in my '05 F150 came out looking like that at about 9K miles and it also had lots of metal in it and on the magnet. I've dumped a lot of diffs in my day and that fairly normal. Most of the wear metals come at the beginning. Good to change it early. I truly believe it will have an effect on longevity.

As to color, when you look at base oil, before the additives and dyes are put in it, it's nearly clear. My thought is that the oil Ford uses doesn't have any dyes in it. To the extent that it's not clear, that's the additives. Maybe that saves them a buck or two on the oil. As good a guess as any ( : < ).

 

[Boomer]

Is it possible that some gear set up gunk was used in the front diff at the factory and it colored the gear oil? Won't hurt anything but it could explain the color.

 

[Ken2]

Sure looks like water in that one sample. If the new oil quickly turns milky, I'd take the rig in for warranty repairs on a leaking gasket or seal.

Schaeffer's #267 80W-90 syn-blend gear oil contains powdered MoS2 in suspension. The Motorcraft product should not look this way. Before anyone says otherwise, #267 is suitable for clutch-type limited slip differentials as stated on the label and my experience for about 70,000 miles.

 

[Jim Allen]

The front and rear diffs on Fords use different oil, which could account for the difference in color.The rear is a 75W140 and the front is a 75W90. I have seen several, mine included, that were that light color and I know they were not emulsified. My front fluid came out dark like his did too. Don't assume the factory installs the same off-the-shelf Motorcraft products you can buy at stores, so the dyes and colors might be different. The last time I checked (a long while back), factory fills were Conoco Phillips oils that had no direct MC equivalent product.

 

[CarbonSteel]

Originally Posted By: Ken2
Sure looks like water in that one sample. If the new oil quickly turns milky, I'd take the rig in for warranty repairs on a leaking gasket or seal.

I could accept that except the truck has not been in any water (yet). I am tending to believe this is the normal color of the oil, but the UOA will tell the tale when I receive the results.

 

[wtd]

Years ago when I changed the front diff fluid in my 98 chevy K1500 for the first time at 20,000 miles, it looked like the fluid out of your front diff. I thought it had water in it. I put Mobil 1 diff fluid in the front and when I changed it next, it looked like that again. I don't use my 4x4 that often and I figured it was condensation buildup from non use. The last time I changed it, it looked normal so I don't know what to think.

Wayne

 

[PDX2500HD]

Interesting color on that first one.. Does look like water contamination but that's highly unlikely if you never go under water with the rear dif.

I'm thinking of putting Royal Purple 85/140 fully synthetic in the rear diff, anyone have any ideas on using an 85W instead of the 75W in moderate to cool climate? I am worried the additional protection benefit of the thicker oil will be mitigated by the poorer cold flowing properties.

 

[ac_tc]

It´s not that unusal to find "watered oil" in
front axles. If you bare uses the fwd the axle
wont get warm and never get rid of condensation
inside it.
I always find "milky" oil in my front end
and it seems to live fine with that.