Differential Lube Change

[Alan Reagan]

Did my differential this weekend and since I couldn't find 75W-85 anywhere, I went with the 75W-90. I sucked out the fluid instead of pulling the covers. The covers were pulled last time so I didn't see a need. When I pulled the plugs, there was very little metallic stuff of the magnets. More of a dust than anything. No slivers. Just a very fine accumulation.

The fluid was the same color as the synthetic that I put back in. Just a shade darker so I was comfortable with sucking it out. Plus, I don't make a big mess when I suck it out versus pulling the cover. The sucker has a pressure drain so I can easily pressurize the tank and then pump it into an old hydraulic bucket for recycling.

I might be imagining things, but the truck has always had a slight whine under load in the rear. The rear gears and bearings were replaced at around 15K because the gear lash was incorrectly adjusted at the factory. The dealership replaced everything. The tech said there would always be a slight noise unless I went with a heavier weight lube. That noise is completely gone. I went back with the Valvoline, full synthetic 75W-90. I don't know what the dealerships use but the Valvoline certainly seems quiet compared to what was in it.

 

[EricViviano]

I have ran 75w-90 in every diff of every truck I've owned. No problems. It works great, pricey though.

I doubt changing the oil would cure a noise, unless it was low.

 

[AH64ID]

Why were you looking for 75w-85? OE Spec is synthetic 75w-90 front and rear.

 

[Shiner]

Why were you looking for 75w-85? OE Spec is synthetic 75w-90 front and rear.

My 17 specs 75-85, but I use 75-90.

 

[AH64ID]

My 17 specs 75-85, but I use 75-90.

Looks like they have changed it up depending on the year. Open a 2015 it calls for 75w-90... Open a 2017 and it calls for 75w-85.

Not sure why they would want a 75w-85 unless they are trying to get a little more fuel economy out of them???

Funny thing is that they don't list a spec for it, unlike the 1500 axle fluids.


EDIT: Okay, so now I've found 2 different 2015 manuals. Once calls for 75w-85 and the other calls for 75w-90... WTF FCA?

 

[EricViviano]

He is right, the owners manual does call for 75w-85 for the 2500/3500. Never seen 75w-85 but ya I'm sure it's some special Mopar fluid that is $30 a quart like the transfer case fluid.

#ad

 

[Shiner]

Looks like they have changed it up depending on the year. Open a 2015 it calls for 75w-90... Open a 2017 and it calls for 75w-85.

Not sure why they would want a 75w-85 unless they are trying to get a little more fuel economy out of them???

Funny thing is that they don't list a spec for it, unlike the 1500 axle fluids.



EDIT: Okay, so now I've found 2 different 2015 manuals. Once calls for 75w-85 and the other calls for 75w-90... WTF FCA?

The fuel mileage thing was my conclusion as well. Really, couldn't come up with anything else to conclude.

 

[AH64ID]

He is right, the owners manual does call for 75w-85 for the 2500/3500. Never seen 75w-85 but ya I'm sure it's some special Mopar fluid that is $30 a quart like the transfer case fluid.

Just depends on what version you open...

I'll be using 75w-90 either way

 

[EricViviano]

@AH64ID - Leave it to RAM, I'm not shocked by this.

 

[Wayne M.]

Slightly off vehicle but not off topic.
I had a moment of weakness and let the dealer drain the diffs in my ‘14 Durango. It was a mistake. The fluid was obscenely expensive and I got mugged in labor. I believe it was 75/85.
Never again.
It was going in for other warranty work, and it just hit 50k, and I want to keep the Max Care policy in check.

 

[Alan Reagan]

Mine called for 75W-85. No way I was paying $50+ a quart. The fluid was not low but the fluid I pulled out didn't seem as viscous as the 75W-90 and the noise is gone. It was a low whine, usually when climbing long hills.

I agree, the change should not have stopped it, but it's gone. The spec called for is Synthetic GL-5.

I called a friend that owns a tractor trailer repair shop here and asked him about the whine disappearing. He said it's probably the additives in the Valvoline. Makes sense. I looked online to see if any others had a slight whine disappear and a site discussing Redline 75W-90 had several posts regarding low whines under load disappearing completely. Before the change to Valvoling, mine was almost inaudible. After having my rear end replaced because of the whine, I was sensitive to it. Now it's gone. I'm happy. Life is good.

 

[Cummins12V98]

I run 75-90 front and 75-110 rear since I tow 33-35K combined. Both lubes are SevereGear. Factory is JUNK!

I always remove the covers. Easy to get all the old lube out and inspect the gears. The gasket is reusable.

 

[sag2]

The Mopar 75w-85 full synthetic PN 68210057AB if $17.35 per quart retail. Dealer cost $10.40.

 

[Newsa]

Why were you looking for 75w-85? OE Spec is synthetic 75w-90 front and rear.

They switched the spec on rear diff fluid to 75w-85 sometime after 2013. I think maybe 2016-2017?

Surprised many of us. And they may have went back and retroactively changed previous years online manuals.

 

[gsbrockman]

Just depends on what version you open...

I'll be using 75w-90 either way

It depends on which revision of the manual you are looking at. The later 2015 manuals began listing the 75W85 GL5.

 

[Alan Reagan]

The Mopar 75w-85 full synthetic PN 68210057AB if $17.35 per quart retail. Dealer cost $10.40.

I believe you, BUT, the dealer here had quoted me $47 and change and that's with a military discount. I asked about it when I picked up the transfer case fluid last month.
No way I was paying that.

 

[RVTRKN]

What transfer case fluid are you using?

 

[AH64ID]

Amsoil ATF

 

[RVTRKN]

I went to Mobil Delvac 50 synthetic trans fluid. I know your under warranty, but too thin of oil for me.

 

[AH64ID]

I went to Mobil Delvac 50 synthetic trans fluid. I know your under warranty, but too thin of oil for me.

I ran it on my 05 too. Fluid din't show signs of being too then when I would change it.