2020 1500 Classic - Rear Diff Whine

[hellcat287]

Noticed a pretty good whine in the rear diff of my 2020 1500 Classic (3.21 rear end) in the morning temps (around 40 - 45F); mostly accelerating from a stop. It will slowly go away as the rear end warms up. Took it to the local dealer and they "cannot replicate".

Thinking about changing the rear end fluid since the truck almost have 50K and I don't have a full history (I'm the third owner.) I don't have a manual but from what I've read the correct type is 75W-90. Wondering if I went with a little thicker fluid 75W-140 that might quiet things down a little bit and provide better protection. I live in Las Vegas so it gets hotter here than colder.

Also, can't find the torque specs for the drain plug. I've seen 24, 32, 44 and 60 - quite a spread!

Would appreciate any input on the subject.

Thanks!

 

[ThunderMug95]

Noticed a pretty good whine in the rear diff of my 2020 1500 Classic (3.21 rear end) in the morning temps (around 40 - 45F); mostly accelerating from a stop. It will slowly go away as the rear end warms up. Took it to the local dealer and they "cannot replicate".

Thinking about changing the rear end fluid since the truck almost have 50K and I don't have a full history (I'm the third owner.) I don't have a manual but from what I've read the correct type is 75W-90. Wondering if I went with a little thicker fluid 75W-140 that might quiet things down a little bit and provide better protection. I live in Las Vegas so it gets hotter here than colder.

Also, can't find the torque specs for the drain plug. I've seen 24, 32, 44 and 60 - quite a spread!

Would appreciate any input on the subject.

Thanks!

Just make sure you clean off the drain plug threads. Its steel on steel, so just get it snug with new RTV on it. Its a drain plug, so its not like its called upon to support movement like a suspension fastener. I just replaced my diff fluids this weekend. Front diff and t-case (if you have them) do not over torque though.

 

[Brent 1955]

Noticed a pretty good whine in the rear diff of my 2020 1500 Classic (3.21 rear end) in the morning temps (around 40 - 45F); mostly accelerating from a stop. It will slowly go away as the rear end warms up. Took it to the local dealer and they "cannot replicate".

Thinking about changing the rear end fluid since the truck almost have 50K and I don't have a full history (I'm the third owner.) I don't have a manual but from what I've read the correct type is 75W-90. Wondering if I went with a little thicker fluid 75W-140 that might quiet things down a little bit and provide better protection. I live in Las Vegas so it gets hotter here than colder.

Also, can't find the torque specs for the drain plug. I've seen 24, 32, 44 and 60 - quite a spread!

Would appreciate any input on the subject.

Thanks!

Instead of going thicker replace one of the quarts with a quart of Lucas Oil Treatment. It will give you the extra protection that you. need. I don't think there is one I just tighten mine tight. The whining sound means your gears are not aligned properly or there dry when you first start out that is why the noise goes away. That is what the Lucas would be for it leaves an oily coating on the gears.

 

[grizzstang]

I would go the 75W140. You live in a warm climate so you won't have any problems. I run that in mine here. No problems at all.

Find out if you have an LS. If you do get the additive or quality fluid that has the additive in it. I have Redline 75W140 in my LS rear diff.

As for the torque spec on the drain plug no idea. I have only ever put them snug. I personally wouldn't use RTV on it either, I just put them back in dry and snug them down.

 

[HuskerRam]

You‘ll survive on 70W140…that’s what I’ve been using and my climate is just like yours.