Help on Rear Axle Oil
 

I have 2014 GT with Track Pack....hence the TORSEN Diff. I put on new rear brakes and pulled the diff cover and axles to replace the caliper brackets. I noticed the rear axle oil has friction modifier in there. It is my understanding that friction modifier is for clutch-type limited slip diffs, not for TORSEN diffs.

Am I correct? Can I re-fill with just oil, no modifier? I think I heard that Ford's T2R may have clutch plates too, dunno?

Torsen = no modifier, you are correct!

Your Owner's Manual will say to put the friction modifier in the oil. I have the Torsen in my GT500 Track Pack and that's what's in the manual. They are very specific to add it - the Track Pack cars only come with a Torsen, and because they take additional gear oil to fill the pipes for the front-mounted diff cooler, you have to add 6 ounces of FM instead of the usual 4 ounces.

No modifier check torsion site .

Interested to see how this one plays out - I would like to change rear diff fluid too, seems like he owners manual and TORSEN website disagree

What "front mounted differential cooler"???

Someone has been telling you fairy tales...:grin:

And it certainly won't hurt anything to put friction modifier in a torsen diff, just doesn't need it.

The friction modifier is so the clutch plates don't chatter in a limited slip diff, yours and my soon to be stangs don't have plates they have gears and springs. I would not put it in ,just use a good syn gear lube.I like red line products myself!

Yeah, I don't think I will add it. I think Ford just got cheap. They realized it won't hurt it, so they just keep one diff filler station on the assembly line. Why bother with a second tank of pure oil they're thinking, I guess. Although, I wonder if FM has some quality, by coincidence, that it allows the oil to manage heat better...just a silly a$$ guess, but why would Ford spend the money to fill cars with it that don't need it? Could it just be convenience on the production line?

Beside, that FM stuff smells like something died! :drool:

Thanks for the help.

That FM is probably possum grease.

It's a 2014 GT500 with the Track Pack option. It comes equipped with a 662 horsepower oil heater! :)

The cooling duct on the passenger's side of the lower opening on the front valence below the bumper feeds the diff cooler radiator.

I won't argue with your logic to leave it out; I agree with your logic on the prospect of the "just one way to do it" in manufacturing but they don't actually do it that way for some reason. First, why bother making it two separate items - just blend them from the supplier and forget about the extra bottle. But they didn't do that.

The other issue, again unique to the GT500, is the gear oil itself. Ford equips the GT500 diff with a 75w-85 diff lube - the same viscosity as many manual transmissions. And, even when they go to the trouble of installing a completely different diff lube, they still add the extra FM to it, 4 ounces for the regular diff and 6 ounces for the track pack (you know, the one with the front-mounted diff cooler).

What the Torsen website actually says about OEM T2 installations is to "follow the owner's manual" regarding FM. For the aftermarket units, they say to leave it out, but otherwise it's the OEM's choice.

The only other theory I could think of is Ford believes the FM helps preserve the pinon and axle seals longer than pure oil. (?) Otherwise, I am totally confused as to why they'd require FM on a non-clutch type diff.

Money ! Sure will sell a lot of it . We stang owners tend to take care of our cars , how many people change there rear end fluid.

This is what I used when I changed it out at 10k miles, a custom-blended oil and it had friction modifier pre-mixed in:

Attachment 197822

Just checked Redline and they have a FM in there gear oil. I think any good gear oil will have some type of FM in it . I wouldn't worry about it to much, I have no used it and not no real difference , no breakdowns.

"Partnerships"
 

I often just think Ford (everyone really) just has partnerships with other business/products. You all remember the BP symbol on your fuel cap. I am sure other fuel was find, but somehow Ford though BP was best...whatever. :bs: And of course, their own Motorcraft parts on the only ones "recommended" in most cases...again, whatever. I don't have a problem with product promotion...I have a problem when that clouds the real issue...like what oil, fuel to use, or whether or not to use FM in a diff without a friction-based component like a clutch device. Whatever.

It all comes with the territory of being an car enthusiast and that's why these sites and the Mustang community is so great. :nice:

+1 well said !