Torsen Diff Fluid

[dubster99]

Any PP owners change their fluid yet? I've heard a few stories of people changing pretty early and being glad they did, seeing some debris in the fluid. Anybody seen the same thing? What fluid did you go with?

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[sandeale]

mobil 1 75w90, noticed a few shavings (normal break-in junk), i've not noticed any additional noises from the fluid change, I just changed all the fluids at 2000 miles, and mobil 1's diff fluid ranked pretty high in comparison tests and was almost as good as amsoil and I didnt have to wait for my local amsoil supplier to order it.

 

[EXP Jawa]

You will always see debris in the axle oil after break in for a brand-new system, usually mushy silver metal paste on the magnet. Keep in mind that most of what you're seeing in the axle is coming from the ring & pinion (not the Torsen). It seems like it used to be that manufacturers recommended an axle oil change after their break in period for that reason, but now it seems like everything is "fill for life".

As far lube goes, the diff will operate just fine in most any gear lube. Ford uses their new Gen-3 75W85 synthetic, mainly for fuel economy reasons. But the differential's torque bias ratio is tuned in that fluid and the fluid definitely has impact on the result. So if you do change to something else, be aware that you are also changing the performance of the Torsen to an extent. You probably wouldn't notice under most conditions though.

One other thing to note - as I said, the diff will run in whatever. The ring and pinion is much more sensitive to lube type and condition. I typically tell people to refer to the R&P manufacturer for lube recommendation rather than the diff, as the diff will work in whatever makes the ring and pinion happy.

 

[gsxr1300]

EXP Jawa
Is there a fluid that you prefer for our application?

 

[jasonstang]

Torsen is pretty easy on the fluids. Any fluids with the correct rating and thickness will work. It's not a clutch type diff so no friction modifier is needed.

 

[dgc333]

There was a TSB back around 05 that said to use 75w-140 for all service on the 8.8 rear end. On the FRPP web site the instructions for ring and pinion changes on the 8.8 to use 75w-140 and that is what the provide.

When I changed mine I used 75w-140. No noticeable fuel mileage hit and slightly quieter rear end.

Dave

 

[EXP Jawa]

EXP Jawa
Is there a fluid that you prefer for our application?

If you're asking if there's an official recommendation - yes, the Ford Gen-III 85W95 lube that the axle was validated in (the old 75W140 is now obsolete). Keep in mind that the diff is just one part of the axle system, and other important components share that lube. The carrier and pinion bearings depend on the lube, but even more importantly, so does the ring & pinion set. The later is much more sensitive to lubrication than the diff is (which, as others mentioned, will work fine in most any suitable oil). For that reason, I almost always tell people to refer to the R&P manufacturer's recommendation for lube. In this case, that manufacturer is, of course, Ford.

If you're asking me if I have any personal preference, not really. In my experience, most any of the reputable brands on the market is pretty equivalent, at least as far as the performance of my product is concerned. I would stay near the original spec in terms of viscosity, as that has bearing on locking performance, but actual branding is unimportant to me.

RE: friction modifier, a few comments. The differential is not a clutch pack unit, as noted, but modifier additive is still used in the OEM fill. It is an NVH countermeasure, as in certain conditions, the diff occasionally exhibited a "moan" noise in a very low torque, low speed, full lock turn. The modifier gets rid of this, and in order to limit the number of warranty claims on normal-functioning parts, it gets used from the start. You certainly can run without it, and if you pick up the noise, add it back in if so inclined. The noise itself is a friction-generated sort of squeak, characteristic of turning a helical gear under light load against a hardened surface. Essentially, they all do it, it just isn't always audible.

 

[Knight5.0]

So you would only recommend ford fluid not Royal purple, Amsoil, or mobile?


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[ForTehNguyen]

put Mobil 1 75W90 in mine, the factory fill was dark gray from the break in. Only have 4200 miles. Bottle said it already has limited slip friction modifiers.

 

[EXP Jawa]

So you would only recommend ford fluid not Royal purple, Amsoil, or mobile?


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Well, like I said, officially the Ford oil is what the axle system was validated in. It represents a "safe" baseline. Other brands like you mention are well-regarded, reputable products. As far as the diff goes, yes, I would say they're fine - though I have zero data as to what impact they'll have on performance. But I would still suggest that you refer to Ford - or Ford Racing - about using them with the OEM (since FRPP resells OEM parts) ring & pinion.

 

[jasonstang]

put Mobil 1 75W90 in mine, the factory fill was dark gray from the break in. Only have 4200 miles. Bottle said it already has limited slip friction modifiers.

Not that torsen needs friction modifiers unlike clutch type LSD. I wonder if I can find a magnetic drain bolt to keep metal from floating inside the diff.

 

[EXP Jawa]

Not that torsen needs friction modifiers unlike clutch type LSD. I wonder if I can find a magnetic drain bolt to keep metal from floating inside the diff.

RE: friction modifier, a few comments. The differential is not a clutch pack unit, as noted, but modifier additive is still used in the OEM fill. It is an NVH countermeasure, as in certain conditions, the diff occasionally exhibited a "moan" noise in a very low torque, low speed, full lock turn. The modifier gets rid of this, and in order to limit the number of warranty claims on normal-functioning parts, it gets used from the start. You certainly can run without it, and if you pick up the noise, add it back in if so inclined. The noise itself is a friction-generated sort of squeak, characteristic of turning a helical gear under light load against a hardened surface. Essentially, they all do it, it just isn't always audible.

Also, I'd be surprised if the standard fill plug in the carrier wasn't already magnetic. That's pretty standard practice.

 

[Banjo]

When I changed the fluid in the rear end of my EB PP the plugs were definitely magnetic. There was grey sludge stuck on both of them.

 

[dubster99]

How much fluid does it take to fill?

 

[ForTehNguyen]

1.7qt or so

plugs are magnetic but they dont stick out long enough or have enough surface area to collect more material. Another good reason to change out your diff fluid anyways. Mine was pretty dark and you can definately see the fine particles.

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