Rear diff oil

[basinite]

I assume you are taking about limited slip differential? If so, I have no clue to be honest if I have that or not but sounds like I need to change out the fluids anyway.

The easiest way to know is to jack up the rear end and spin the tires. If both tires spin in the same direction you have a LSD, if they spin in opposite direction you have an open differential*** (unless the clutch plates are worn). You will want to know for sure if you are going to change the oil yourself, since you will need to add a special additive if you have an LSD rear end.

***There is another thread on here where this is being debated and one poster claimed the new LSD's will spin in opposite directions like an open differential. I'm doubtful about this, so I'm going to jack up mine and test it this weekend. I just bought a new 2020 Willys and it has the LSD.

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[Jimmy_jak]

That video came to mind, but I thought this guy was on The Naughty List.

why a naughty list?

 

[mgrowc1]

The easiest way to know is to jack up the rear end and spin the tires. If both tires spin in the same direction you have a LSD, if they spin in opposite direction you have an open differential*** (unless the clutch plates are worn). You will want to know for sure if you are going to change the oil yourself, since you will need to add a special additive if you have an LSD rear end.

***There is another thread on here where this is being debated and one poster claimed the new LSD's will spin in opposite directions like an open differential. I'm doubtful about this, so I'm going to jack up mine and test it this weekend. I just bought a new 2020 Willys and it has the LSD.

Based only on research it seems that since I have a rubicon I have tru loc. Thus, I don’t need the additive. Does this make sense? Also looks like I need 75w85 based on online manuals I read. I should note I have the tow package though so read that it may be different? I got this option and literally have never used it and if I ever do it will be very limited.

Mark

 

[basinite]

Based only on research it seems that since I have a rubicon I have tru loc. Thus, I don’t need the additive. Does this make sense? Also looks like I need 75w85 based on online manuals I read. I should note I have the tow package though so read that it may be different? I got this option and literally have never used it and if I ever do it will be very limited.

Mark

You are correct. Consider yourself lucky, lockers are the best. I'm not sure how mechanically inclined you are, but changing the oil in differentials is really easy. I can still remember helping my dad do it when I was a pup. If you still don't feel comfortable doing it after watching the YouTube videos, just pay the $$$ and have the dealership do it.

Sometimes peace of mind is priceless.

 

[melendez69]

why a naughty list?

Legend has it he's been banned for a variety of reasons. It's public here in the forums.

 

[IceBerg]

You can buy take off axles for about $1k

For that price you should just replace the whole axle instead of changing the fluid.

 

[melendez69]

Based only on research it seems that since I have a rubicon I have tru loc. Thus, I don’t need the additive. Does this make sense? Also looks like I need 75w85 based on online manuals I read. I should note I have the tow package though so read that it may be different? I got this option and literally have never used it and if I ever do it will be very limited.

Mark

If you decide to do this on your own, you can also use 75w 90 front & rear. If you plan to tow frequently, consider 75w 140 for the rear.
And I agree with @basinite ... you can't go wrong with peace of mind.

 

[mgrowc1]

Thanks all. It does seem crazy easy to do actually. I am not mechanically inclined at all but used to change my own oil on my motorcycle so this shouldn’t be an issue.

The only confusing thing is figuring out what axel I have and what weight fluid to use and if I should have the additive added in etc.

 

[word302]

Thanks all. It does seem crazy easy to do actually. I am not mechanically inclined at all but used to change my own oil on my motorcycle so this shouldn’t be an issue.

The only confusing thing is figuring out what axel I have and what weight fluid to use and if I should have the additive added in etc.

You have the 210 front/220 rear. No additive. 75w-85. Red line makes a synthetic. This is easier than an oil change.

 

[IceBerg]

And do NOT worry about brand of oil to use. Just get the cheapest 75w-85 that you can find.

 

[jrohan07]

Question for CARBONSTEEL

I would recommend that everyone with a JL change their rear axle oil at 15K or less and move up to a higher viscosity oil. I am running 75W-110 in the front as it is the viscosity that 75W-90 used to be before the SAE J306 tables were updated a while back. I run 75W-140 in the rear axle. Amsoil Severe Gear has given me great service through the years (especially when towing heavy) and so I highly recommend it.[/QUOTE]

So my question is "can you run the 75W-140 in both the front and rear with no issues?

What about synethic brand? Better?

I had my 2018 Sport S w/LSD changed by the dealer front and rear to 75W-140 on his advise as he stated this is really great for towing even if you don't tow for the LSD.
Did not charge me..said under warranty....

It did however stop the clunking sound from the rear drive shaft lashing with bad OEM gear oil that was black at 9000 miles.

Now 22000 miles and have not had any issues.

 

[CarbonSteel]

I would recommend that everyone with a JL change their rear axle oil at 15K or less and move up to a higher viscosity oil. I am running 75W-110 in the front as it is the viscosity that 75W-90 used to be before the SAE J306 tables were updated a while back. I run 75W-140 in the rear axle. Amsoil Severe Gear has given me great service through the years (especially when towing heavy) and so I highly recommend it.

Question for CARBONSTEEL

So my question is "can you run the 75W-140 in both the front and rear with no issues?

What about synthetic brand? Better?

I had my 2018 Sport S w/LSD changed by the dealer front and rear to 75W-140 on his advise as he stated this is really great for towing even if you don't tow for the LSD.
Did not charge me..said under warranty....

It did however stop the clunking sound from the rear drive shaft lashing with bad OEM gear oil that was black at 9000 miles.

Now 22000 miles and have not had any issues.

You could run the same viscosity in both with no issues, though the front axle will see less load overall than the rear which is in operation 100% of the time. Some will argue that a heavier oil like 75W-140 will reduce MPG, but I would posit that on any 4x4, the gear oil is the least of what reduces MPG.

Heavier viscosity provides more protection and synthetic oils can withstand higher operating temperatures than conventional oil. I have used Mobil 1, Valvoline, Castrol, and Amsoil. I tend to gravitate to Amsoil for its overall protection, flow capabilities, and it helps control "thermal runaway" (https://www.amsoil.com/newsstand/articles/a-closer-look-at-gear-lube/). I prefer synthetics and with the small capacity of these axles (1.3QTs in front M210 and 1.5 QTs in rear M220), I want all the protection that I can find.

 

[wheels082]

I also use the Amsoil Severe Gear. You can get the squeeze bottles so you don't need a pump.
https://www.amsoil.com/shop/by-product/gear-lube/severe-gear-75w-90/?code=SVGPK-EA/?zo=226468

 

[GreyFox]

You have the 210 front/220 rear. No additive. 75w-85. Red line makes a synthetic. This is easier than an oil change.

Is this something I can do on my JKU also? The dealer wants almost $600 for both front and rear now that I've got 50,000+ on it. After reading these threads, I think I can do this on my JL

 

[word302]

Is this something I can do on my JKU also? The dealer wants almost $600 for both front and rear now that I've got 50,000+ on it. After reading these threads, I think I can do this on my JL

Yes. Super easy.

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