Gear oil

[Deleted member 30519]

I just got a re-gear and the shop said they use 85w140 non synthetic. What's the best kind of synthetic? I also read on another old thread that if you have the sport limited slip differential it needs some kind of additive? I have a sport with the Dana 44s.

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[jac04]

If the shop recommended 85W-140 non-synthetic then I would follow their recommendation. That way, if there is any warranty issue them you can tell then that you used what they told you to. Also, if you are regularly wheeling your Jeep then you will likely be changing the diff oil fairly often, and the 85W-140 conventional oil is reasonably priced.

ECGS recommended Lucas conventional 85W-140 for my custom-built rear D44 for my JK, and offered a 5-year unlimited mileage warranty on it:
https://lucasoil.com/products/gear-oil/gear-oil/lucas-heavy-duty-85w-140-gear-oil

I think you will find that most synthetic gear oils are 75W-140, but you may find some 85W-140 synthic blend oils.

 

[kevman65]

If you re-gear then you throw out the MOPAR specification and go with gear manufacturer specification.
MOPAR is no longer responsible for your differential.

 

[Deleted member 30519]

If the shop recommended 85W-140 non-synthetic then I would follow their recommendation. That way, if there is any warranty issue them you can tell then that you used what they told you to. Also, if you are regularly wheeling your Jeep then you will likely be changing the diff oil fairly often, and the 85W-140 conventional oil is reasonably priced.

ECGS recommended Lucas conventional 85W-140 for my custom-built rear D44 for my JK, and offered a 5-year unlimited mileage warranty on it:
https://lucasoil.com/products/gear-oil/gear-oil/lucas-heavy-duty-85w-140-gear-oil

I think you will find that most synthetic gear oils are 75W-140, but you may find some 85W-140 synthic blend oils.

Thanks man. I think I'm gonna go with the 85W-140 Lucas conventional since they have it right at my local auto zone. Do you know what kind of additive I should use for the limited slip? Is it bad to let the new gears brake in after 500 miles before getting the fluid changed? I think I'm close to 500 miles but my shop can't get me in until Monday.

 

[jac04]

I suggest double-checking with Lucas to see if the 85W-140 has limited slip additives. It should. Some of my bottles state "Excellent for use in limited slip differentials. No special additive needed.", but other bottles only have "Excellent for use in limited slip differentials."

All I have is e-lockers, so I've never really worried about it.

I would try to get the fluid changed as close to the 500 mile mark as possible. This is only because that is what is recommended and you want to make sure your warranty is good. Changing the diff oil is really easy, and it is a good DIY job if you want to try it yourself.

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