Rear Axle Fluid Chart

[Cobra Jet]

In the vent anyone needs the info, attached is the most recent rear axle fluid fill/capacity chart:

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[Vlad Soare]

Interesting that there's no differentiation between Torsen and TracLok. Same fluid, same capacity, same friction modifier... By the way, does a Torsen really need a friction modifier? I thought only the clutch-type diff did.

 

[ice445]

Interesting that there's no differentiation between Torsen and TracLok. Same fluid, same capacity, same friction modifier... By the way, does a Torsen really need a friction modifier? I thought only the clutch-type diff did.

Nope, Torsen doesn't need a modifier. From the research I did, it seems Ford is only adding modifier to the Torsen cars because it slightly lowers the torque bias ratio which can make the unit quieter and a little better mannered on the street.

The Trak-Lok diff definitely needs friction modifier though. 3.28 ounces to be exact on a fresh fill. I'm currently in the process of figuring out if some of the aftermarket fluids that are supposedly formulated with friction modifier will work properly without causing chatter. The only useful thing I've found so far is that you can add the XL-3 modifier at any time, with any aftermarket fluid. So if you want to use a straight synthetic gear oil and the motorcraft friction modifier, go right ahead. It's actually easier to do that versus hoping a pre formulated limited slip gear oil has the correct proportion of additive.

 

[Deleted member 35644]

I drained & filled my diff late last week with Redline 75W90 (not the NS), and I think I'm getting pronounced chatter. I hear a weird groaning rubbing noise when I turn sharply at very low speeds. Anyone else get this with Redline & no XL-3?

 

[ice445]

I drained & filled my diff late last week with Redline 75W90 (not the NS), and I think I'm getting pronounced chatter. I hear a weird groaning rubbing noise when I turn sharply at very low speeds. Anyone else get this with Redline & no XL-3?

Its pretty normal on these diffs from what I've researched. Most limited slip formulations arent quite enough. According to redline there's no issues adding XL-3 to their fluid. I'd start by adding 2 ounces (half the bottle) and see if it goes away. Don't drive the car much if you can avoid it, chatter is technically bad for the diff.

 

[Deleted member 35644]

Its pretty normal on these diffs from what I've researched. Most limited slip formulations arent quite enough. According to redline there's no issues adding XL-3 to their fluid. I'd start by adding 2 ounces (half the bottle) and see if it goes away. Don't drive the car much if you can avoid it, chatter is technically bad for the diff.

Thanks, that's also what I was wondering, as the dealership has the car right now for a transmission issue. I've got the XL-3 but no way to put it in at the moment, hopefully they won't be driving it around too much.

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