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Rear differential cover with upgraded fluid capacity?

1277 Views 14 Replies 9 Participants Last post by  YnotAJeep
2020 Gladiator Sport S fyi


I have looked (and found) a bunch of upgraded rear differential covers for the new-to-us Gladiator. However, most of these are stronger and more for protection. While I would never shy away from buying something that's "better", my main goal with an aftermarket cover is a higher fluid capacity. We will use the Gladiator to tow and before I replace the rear diff fluid, I thought I'd see what I could find for a new cover. The truck has 47k on it and as far as I can tell the stock fluid in both pumpkins.
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2020 Gladiator Sport S fyi


I have looked (and found) a bunch of upgraded rear differential covers for the new-to-us Gladiator. However, most of these are stronger and more for protection. While I would never shy away from buying something that's "better", my main goal with an aftermarket cover is a higher fluid capacity. We will use the Gladiator to tow and before I replace the rear diff fluid, I thought I'd see what I could find for a new cover. The truck has 47k on it and as far as I can tell the stock fluid in both pumpkins.
You’re saying you want a higher fluid capacity? It’s my understanding even with an aftermarket cover you still only want to fill the diffs with the recommended amount in the manual. Any more and it might just burp it out the breather hose.
 

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You’re saying you want a higher fluid capacity? It’s my understanding even with an aftermarket cover you still only want to fill the diffs with the recommended amount in the manual. Any more and it might just burp it out the breather hose.
You still fill it to the same height but sometimes you can find them that make more room inside allowing for more fluid. It's more common in the truck world but idk if anything is available for the jl/jt
 

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You need to be careful, and understand that the internal shape of the diff cover plays a very important role in the lubrication of the differential. The ring gear picks up oil between it and the cover, and then 'throws' it into the pinion bearing area, providing the pinion bearings with proper oil flow. This is why the factory diff covers have a funky shape.

So, just because a diff cover allows for more oil capacity does not mean it is better, and it could actually cause problems.
 

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You need to be careful, and understand that the internal shape of the diff cover plays a very important role in the lubrication of the differential. The ring gear picks up oil between it and the cover, and then 'throws' it into the pinion bearing area, providing the pinion bearings with proper oil flow. This is why the factory diff covers have a funky shape.

So, just because a diff cover allows for more oil capacity does not mean it is better, and it could actually cause problems.
AEV said their diff cover is molded to the same shape and capacity as the OEM covers.
 

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AEV said their diff cover is molded to the same shape and capacity as the OEM covers.
Yes, and it's one of the few covers I'd consider.

The OP stated "my main goal with an aftermarket cover is a higher fluid capacity", so I just wanted to be sure they were made aware of potential issues.
 

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Just change the oil more often. what little the diff cover adds won't really matter and the factory cover is designed for that diff correctly.
 
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Two things:

47k on these axles with factory fill fluid is risky. Have you seen the fluid guys drain out of these with 15k on the clock? It's as black and contaminated as coal. I can't imagine what your fluid looks like pushing 50k. Early break-in service should always been done early in a truck's life to benefit it long term.

More fluid doesn't equal cooler fluid. It simply means the fluid will heat up more slowly to operating temp, but then also cool down more slowly after you park. There is zero benefit. Same is true of the aftermarket transmission fluid pans that are for sale.
 

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Two things:

47k on these axles with factory fill fluid is risky. Have you seen the fluid guys drain out of these with 15k on the clock? It's as black and contaminated as coal. I can't imagine what your fluid looks like pushing 50k. Early break-in service should always been done early in a truck's life to benefit it long term.

More fluid doesn't equal cooler fluid. It simply means the fluid will heat up more slowly to operating temp, but then also cool down more slowly after you park. There is zero benefit. Same is true of the aftermarket transmission fluid pans that are for sale.
40k is the first recommended oil change on the axles. Unless they get water in them.
 

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47k on these axles with factory fill fluid is risky. Have you seen the fluid guys drain out of these with 15k on the clock? It's as black and contaminated as coal. I can't imagine what your fluid looks like pushing 50k. Early break-in service should always been done early in a truck's life to benefit it long term.
I agree with 100%. If you want stuff to last as long as possible you need to do an early and then regular fluid changes.
 

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I have wondered if the heavy cast covers just hold in the heat more keeping the oil hotter longer.
 
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