That’s it, I’m confused! Gear oil

[chri5k]

Well I installed the diff cover today. The Mobil 1 fluid that had been in there for about 30K miles (6K towing 13K trailer) smelled a slight bit burned. Not as bad as the OEM fluid that had been in there before the Mobile 1. The install went smoothly with no hiccups. The diff cover actually sits about 1/8" above the bottom of the diff itself. The back edge of the flat spot on the bottom of the diff is radiused and the Banks cover meets perfectly where the radius ends. The Amsoil pouches are the bomb for filling the diff. Cut off the tip of the spout and you can curve the top of the pouch 180 degrees to get the nozzle in the fill hole before tipping the pouch up. the gear oil flows smoothly into the diff collapsing the pouch as it empties. No need to even squeeze the pouch.

 

[DarthMegaHD]

Did the rear diff so far. Took about 3.5 quarts to fill line. I used an Allen key with its 90 degree angle as a dip stick. Hardest part was getting around those brake lines attached to the plate. That was a dumb design.

 

[DarthMegaHD]

Just did the front diff. Way quicker and easier than the rear. Would have been even quicker if I hadn’t forgotten to locktite the bolts before I torqued them all down. There’s no fill line for the front so I filled until it streamed out. Ended up with a whole unopened quart and maybe 1/3 of another. I had 7 on hand so I don’t get the math but whatever. Might be placebo but it feels like it drives buttery smooth now

 

[68PowerWagon]

Just did the front diff. Way quicker and easier than the rear. Would have been even quicker if I hadn’t forgotten to locktite the bolts before I torqued them all down. There’s no fill line for the front so I filled until it streamed out. Ended up with a whole unopened quart and maybe 1/3 of another. I had 7 on hand so I don’t get the math but whatever. Might be placebo but it feels like it drives buttery smooth now

So you only used about 2 quarts for the front diff?

 

[pacofortacos]

I know this is a bit older thread, but the main reason you see people using 75-140 is because that is what is rec. with a 1500 rearend.
2500 doesn't need it - it has a much more stout rear diff than the 1500.
As said the 2500 rec. is 75-90.

 

[68PowerWagon]

I know this is a bit older thread, but the main reason you see people using 75-140 is because that is what is rec. with a 1500 rearend.
2500 doesn't need it - it has a much more stout rear diff than the 1500.
As said the 2500 rec. is 75-90.

Actually 75W-85

 

[2012Cumminsguy]

I put amsoil severe gear 90W front and back in my 2012 and change it every two years, never ever an issue.

 

[DarthMegaHD]

So you only used about 2 quarts for the front diff?

Sounds about right

 

[Gr8bawana]

Just did the front diff. Way quicker and easier than the rear. Would have been even quicker if I hadn’t forgotten to locktite the bolts before I torqued them all down. There’s no fill line for the front so I filled until it streamed out. Ended up with a whole unopened quart and maybe 1/3 of another. I had 7 on hand so I don’t get the math but whatever. Might be placebo but it feels like it drives buttery smooth now

Yes it is all in your head. Just like those who say their truck runs better after an oil change or after it's been washed.

 

[CoZo6]

trust me, I’ve been searching the forums so please don’t tell me about using the search to find a post you saw one time. So it’s clear the favorite gear oils are amsoil severe gear and redline. Got it. Hard to find locally but I’ll order. But the weights? I have 4.10s in my 2500 and the manual recommends 75w95 but it seems most recommend 75w140 for the rear? Why would you want a different weight for the rear when they’re the same ratio? Even if the answer is “because science” that’s fine, I just don’t want to buy the wrong weight. Also, last thing. It seems the amount of oil differs quite a bit. I know there’s a fill line on the back plate. The amount to this line I’ve gathered is anywhere between 2.5 and 5 quarts for the rear. If both front and rear were to take the same weight it could save some headache and I’d just buy 3 gallons or something but that’s not the case. Many on here recommend different weights. Someone please spell this out very clearly for me, I’m a Marine I need very clear instructions lol. I’ve watched the YouTube videos and they vary or leave details out.

I’m leaning towards 3 quarts of redline 75w95 for the front and 4 quarts of redline 75w140 for the rear. If anyone thinks I’m dead wrong or need this or that tweak, by all means please let me know, thanks

Just completed my gear oil change 2 weeks ago. 2017 2500 Big Horn Black, 4.10 gears like yours. Manual recommended 75W-85 (my recommendation was Redline) and that’s what it got. Interesting that it changed from your 2016 to my 2017. But then you have the 6.4 Mega and I have the 5.7 short box.

 

[pacofortacos]

Actually 75W-85

In the rear? I guess they changed it.

That's what in the front on a 1500 also.

 

[68PowerWagon]

Yes it is all in your head. Just like those who say their truck runs better after an oil change or after it's been washed.

The best is when you change oil, wash it, & fill it full of gas. Drives like a new truck again.