Differential Oil, 75W85 or 75W140 ???

justinB

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I have nearly 10k miles on the 392. I'm wanting to replace my front & rear differential oil. Regarding the rear dif, the 392 performance manual states to use 75W140 if you have a M200 DRZ sales code. If you have a M220 DRE/DRF sales code you're supposed to use 75W85.

I'm going through all my paperwork with no prevail. Short of actually calling the dealer, where/how do I find out if I have the M220 or M200?

Thanks in advance,
~justin
 

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I have nearly 10k miles on the 392. I'm wanting to replace my front & rear differential oil. Regarding the rear dif, the 392 performance manual states to use 75W140 if you have a M200 DRZ sales code. If you have a M220 DRE/DRF sales code you're supposed to use 75W85.

I'm going through all my paperwork with no prevail. Short of actually calling the dealer, where/how do I find out if I have the M220 or M200?

Thanks in advance,
~justin
You have a 392, they all have M220. Only difference is 2021 have a drain plug 2022 don’t.
 
You have a 392, they all have M220. Only difference is 2021 have a drain plug 2022 don’t.
You have a 392, they all have M220. Only difference is 2021 have a drain plug 2022 don’t.
Thank You for the reply. With that, I assume I have the Trac-Loc limited slip, and as such I'll require a friction modifier.?. Any suggestions on a brand to use... or perhaps use gear oil with the modifier already added?

In this instance, I guess I'm glad I have a 2021. How are people draining the 2022's with no drain plug? A suction hose through the inlet plug?
 
Thank You for the reply. With that, I assume I have the Trac-Loc limited slip, and as such I'll require a friction modifier.?. Any suggestions on a brand to use... or perhaps use gear oil with the modifier already added?

In this instance, I guess I'm glad I have a 2021. How are people draining the 2022's with no drain plug? A suction hose through the inlet plug?
No, Rubicons do not have limited slip. Regardless of engine. One of the reasons I have always bought Rubicons. I hate limited slip diffs in the snow and ice.

So, no friction modifier to add. That being said most quality synth gear lube includes It.

Also 2022 M220 will have to change fluid the old fashion way. Pull the cover, which many will say is better than draining. But if you just want to do a quick drain and refill since you forded a river or something, quick change it is not…. No RTV tho, that was a pain. They have reusable gaskets.
 
No, Rubicons do not have limited slip. Regardless of engine. One of the reasons I have always bought Rubicons. I hate limited slip diffs in the snow and ice.

So, no friction modifier to add. That being said most quality synth gear lube includes It.

Also 2022 M220 will have to change fluid the old fashion way. Pull the cover, which many will say is better than draining. But if you just want to do a quick drain and refill since you forded a river or something, quick change it is not…. No RTV tho, that was a pain. They have reusable gaskets.
Awesome. I really do appreciate your knowledge.
Thank You Kindly :)
 
Awesome. I really do appreciate your knowledge.
Thank You Kindly :)
One last tip from an old timer…. Always remove the fill plug before removing the drain plug. You want to make sure you can refill before you drain! It is a bummer when you can’t get the fill plug out after it is empty! Makes taking it to a shop to get help more challenging! Don’t ask me how I know;)
 
One last tip from an old timer…. Always remove the fill plug before removing the drain plug. You want to make sure you can refill before you drain! It is a bummer when you can’t get the fill plug out after it is empty! Makes taking it to a shop to get help more challenging! Don’t ask me how I know;)
HaHa! OK. Will do, lol.
 
No, Rubicons do not have limited slip. Regardless of engine. One of the reasons I have always bought Rubicons. I hate limited slip diffs in the snow and ice.

So, no friction modifier to add. That being said most quality synth gear lube includes It.

Also 2022 M220 will have to change fluid the old fashion way. Pull the cover, which many will say is better than draining. But if you just want to do a quick drain and refill since you forded a river or something, quick change it is not…. No RTV tho, that was a pain. They have reusable gaskets.
Last quick question. I've always been a Lucas Oil fan. Think it'd be ok to go with a synthetic 75W90? This verse the recommended Mopar 75W85...
Thanks
 

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Last quick question. I've always been a Lucas Oil fan. Think it'd be ok to go with a synthetic 75W90? This verse the recommended Mopar 75W85...
Thanks
No problem. 75W85 is usually a traditional lube, where 75W90 is typically synthetic lube. I would always recommend a synthetic for diffs since they don’t get changed as often.
 
No problem. 75W85 is usually a traditional lube, where 75W90 is typically synthetic lube. I would always recommend a synthetic for diffs since they don’t get changed as often.
Perfect. Thank You!!!
 
So, I changed out the front and rear differential oil this last weekend. The front dif had 3.5 cups (.87 quart) and the rear had 5.5 cups (1.37 quarts). In the manual I wasn't able to find the exact amount each dif is/was supposed to have in it; however, that didn't seem like much.?. I did fill it back up nearly level to the inlet plug.

With less than 10,000 miles on the Jeep there seamed to be quite a bit of fine metal particulates on the magnet. I know this being the initial wear, hopefully there will be less the next go around.
 

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So... it seems there are lots of synthetic gear oil choices (Mobile 1, Lucas, Red Line, AMSoil, Mopar, etc). Is there really that much difference?? Prices seem to range from $48/gal to $80/gal or more. I'd love to hear thoughts and comments.
 
So... it seems there are lots of synthetic gear oil choices (Mobile 1, Lucas, Red Line, AMSoil, Mopar, etc). Is there really that much difference?? Prices seem to range from $48/gal to $80/gal or more. I'd love to hear thoughts and comments.
Pick your favorite. Doesn’t need much. If you are towing you want to go a little stiffer in the rear. Sadly the owners manual doesn’t mention that, but the service manual does. 1 Qt for the front and 2 Qts for the rear is all that is needed.
 
So... it seems there are lots of synthetic gear oil choices (Mobile 1, Lucas, Red Line, AMSoil, Mopar, etc). Is there really that much difference?? Prices seem to range from $48/gal to $80/gal or more. I'd love to hear thoughts and comments.
I used to use mobile 1 for years, in all my vehicles, for engine and gear oil. It worked great. On my 2000 Kia Sportage I did notice that at around 120k miles my engine started to tick more frequently and my manual transmission was harder to shift. Sure, there's normal wear I'm considering. Anyways, I talked to my buddy, a trucker and heavy equipment mechanic. He told me I should switch to synthetic Lucas, so I did. I immediately noticed the ticking stopped and my transmission became much easier to shift. It also helped with the small amount of oil I was burning and or leaking. That Sportage has around 200k miles on it now and is still running great, no ticking.
 
So... it seems there are lots of synthetic gear oil choices (Mobile 1, Lucas, Red Line, AMSoil, Mopar, etc). Is there really that much difference?? Prices seem to range from $48/gal to $80/gal or more. I'd love to hear thoughts and comments.
I’m a fan of Mobil 1. I geek out on lubes. I’ve ran Amsoil, Lucas, royal purple, valvoline. I would always check fluid temp, controlling conditions as much as possible As well as weigh the filings. Weighing them doesn’t really say much, as you’ll get more initially and less with time.
I found Mobil 1 and Amsoil routinely ran cooler. Royal Purple was always running the hottest.
 
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I have nearly 10k miles on the 392. I'm wanting to replace my front & rear differential oil. Regarding the rear dif, the 392 performance manual states to use 75W140 if you have a M200 DRZ sales code. If you have a M220 DRE/DRF sales code you're supposed to use 75W85.

I'm going through all my paperwork with no prevail. Short of actually calling the dealer, where/how do I find out if I have the M220 or M200?

Thanks in advance,
~justin
IMG_4414.jpeg
 
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