Definitive answer needed for gear oil.

[Dougstdig]

Since owning my last TJ, that was a 99 model I had it in my mind that the rubicon rear axle was a combination full locking differential when engaged and a LS when not engaged. After doing a search, the only arrival I can don’t relates back to the TJ.

I’m asking this because I’m about to service my `21 JTRD axles for the first time. The owners manual lists 75w85 gear lubricant for the M220. It states if equipped with the Trac-Lok limited slip it also requires a friction modifier additive. So, does the locking differential equipped with the Rubicon package also include a LS when the locker is not engaged requiring the additive or are we good to move forward with a fully synthetic 75w85 with no additional friction modifiers?

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[JTBurns]

I don't own a Rubi and haven't serviced one, but I stayed at a Holiday Inn Express last night, and can tell you it's an open differential when unlocked

 

[jac04]

I’m asking this because I’m about to service my `21 JTRD axles for the first time. The owners manual lists 75w85 gear lubricant for the M220. It states if equipped with the Trac-Lok limited slip it also requires a friction modifier additive. So, does the locking differential equipped with the Rubicon package also include a LS when the locker is not engaged requiring the additive or are we good to move forward with a fully synthetic 75w85 with no additional friction modifiers?

The Rubicon has a Tru-Lok differential front & rear, not to be confused with a Trac-Lok. It is not a limited slip type differential and does not require the additive.

 

[Hootbro]

Rubicon and Mojave with electronic locker do not get the LS additive. I would also add per the Tech Authority information, 75W-140 is also authorized gear oil grade for those with the Trailer Tow Package. This is also the same grade that DANA ships with on the axles they sell aftermarket.

There is also no detriment to going with a fully synthetic 75W-90 over a 75W-85 grade gear oil and opens up a lot more availability options.

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