2025 3500 Rear Diff Noise

[Sco]

The rear diff started making a howling noise at 500 miles when decelerating. The dealer said to run it. I waited until 4300 miles until they replaced the ring & pinion. The new gear set started howling 400 miles after being replaced. The dealer said to keep running it this way. I would like to know what rear end is in the truck. There is no tag on it. I am tired of driving with a noisy rear diff wondering if it will leave me stranded sometime. Has anyone else had this issue? 2025 Ram 3500 Cummins currently 5900 miles

 

[G Mcpherson]

AAM Gears

 

[Sco]

AAM Gears

I don’t know if it is an 11.5 inch rear diff or a 12 inch. The 11.5 takes 75/85 oil & the 12 inch takes 75/140. The mechanic at the dealer would not tell me. He said he just put in what “they” handed him. I am concerned that he put the wrong oil in it.

 

[Xflight29]

The rear diff started making a howling noise at 500 miles when decelerating. The dealer said to run it. I waited until 4300 miles until they replaced the ring & pinion. The new gear set started howling 400 miles after being replaced. The dealer said to keep running it this way. I would like to know what rear end is in the truck. There is no tag on it. I am tired of driving with a noisy rear diff wondering if it will leave me stranded sometime. Has anyone else had this issue? 2025 Ram 3500 Cummins currently 5900 miles

My 2025 3500 with 25K on it has never made any type of sound. At 500 miles I had dealer change the gear oil as I tow heavy with it.

 

[Units]

I don’t know if it is an 11.5 inch rear diff or a 12 inch. The 11.5 takes 75/85 oil & the 12 inch takes 75/140. The mechanic at the dealer would not tell me. He said he just put in what “they” handed him. I am concerned that he put the wrong oil in it.

Pretty sure it’s the 12”. Gear oil recommendations are in your user manual.

 

[AH64ID]

I don’t know if it is an 11.5 inch rear diff or a 12 inch. The 11.5 takes 75/85 oil & the 12 inch takes 75/140. The mechanic at the dealer would not tell me. He said he just put in what “they” handed him. I am concerned that he put the wrong oil in it.

Your build sheet will tell you what axle it has, but I'm pretty sure all 3500's get the 12.0".

The 12.0" only gets 75w-140 in DRW applications, SRW's still get 75w-85. So unless you're a DRW towing at/near max GCW the "wrong" fluid won't cause any issues.

 

[Sco]

Thank you for the replies. It’s a SRW so I can assume it’s a 12 inch that takes 75/85. The owner’s manual wasn’t clear to me & I was unable to find the build sheet when I typed in my serial #. I do find it odd that the noise started both times when I had weight on it but much less than it is rated for. Thank you all again.

 

[raoul_duke]

My 2026 SRW 3500 took a full quart in the rear and half a quart up front when I took it home from the dealer. I’ve seen other people with same issue. I hope it’s not like the push-in-your-fuses issue.