Super tech gear oil

[Wild Bill's ‘98 TJ]

Does anyone know if Super Tech 80w 90 gear oil is ok for limited slip differential?
It is “GL5” but doesn’t say anywhere on the bottle or the internet (that I can find) that it is ok for limited slip.
Thanks!

 

[JKP]

It's fine, but you will need to get some limited slip additive and put it in with the gear oil.

 

[Jerry Bransford]

It's fine, but you will need to get some limited slip additive and put it in with the gear oil.

It's back label confirms it already contains the limited slip friction modifier additive. It's hard to find a GL-5 without it.

 

[JKP]

It's back label confirms it already contains the limited slip friction modifier additive. It's hard to find a GL-5 without it.

The synthetic does, but not the conventional. Conventional only states recommended for LS and does not state that it is suitable for total replacement.

 

[Jerry Bransford]

The back label on the conventional I read clearly states it's recommended for limited slip differentials.

 

[JKP]

Yes, but they all say that as they are suitable for top off of LS diffs that already have additive in the oil. The ones with LS additive specifically state that they are suitable for total refill and contain LS additive.

 

[MountaineerTom]

Yes, but they all say that as they are suitable for top off of LS diffs that already have additive in the oil. The ones with LS additive specifically state that they are suitable for total refill and contain LS additive.

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I found this to be the case recently with conventional Valvoline 85-140 also. No additive, so I added a bottle of MOPAR additive to it.

 

[Jerry Bransford]

Yes, but they all say that as they are suitable for top off of LS diffs that already have additive in the oil. The ones with LS additive specifically state that they are suitable for total refill and contain LS additive.

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We'll have to agree to disagree on the interpretation of that blue label. That it says it's only for unsynchronized transmissions means the friction modifier for clutch-based LSDs that would fuck up transmission synchronizers is present.

 

[JKP]

The syncro (yellow metals) eater is the sulphur in the GL5s. Jeep screwed that up in the FSM and owners manuals for the AX15 by recommending GL5. I really have no idea how the FM would affect the syncros.

 

[Jerry Bransford]

I really have no idea how the FM would affect the syncros.

Enough that they include instructions not to use it when the transmission has synchronizers.

 

[JKP]

All I could find online was the the FM they put in the syncromesh type lubes for MTs is different than the FM used for LSDs.

 

[Vtx531]

I have conventional and synthetic ST in my garage. The synthetic is exactly like post #2. Here is the conventional:

 

[Wild Bill's ‘98 TJ]

Thanks for the info everyone.
I went with a Valvoline that is actually labeled that it contains limited slip additive.

 

[HandOverFist]

For future reference, Amsoil's 75W140 synthetic gear oil tested off the charts vs all others with it's load carrying capacity.