Diff fluid

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Aug 10, 2020
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Friends truck, 2019 Ram 2500 with the 6.7 Cummins, bone stock with 45k miles. Its either hooked up to a gooseneck hauling stuff or pulling his 5th wheel camper that weighs around 17k loaded, 95% of the time. I change the oil every 8k with Delvac 15W40 and a Napa Gold filter, fuel filters every 15k, and air every 30k. I told him we should start changing the tranny fluid and rear diff fluid every 50k and he agreed. I know it calls for 75W85, I was thinking of using either Redline 75W90 or 75W110, or should I stick to the 75W85? Im not sure if he has the AAM 11.5 or 12.0 axle, Ill find out. Also Id like to find the torque specs for the cover. I think its 30 lbs but some have reported bolts snapping at that torque.
 
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Friends truck, 2019 Ram 2500 with the 6.7 Cummins, bone stock with 45k miles. Its either hooked up to a gooseneck hauling stuff or pulling his 5th wheel camper that weighs around 17k loaded, 95% of the time. I change the oil every 8k with Delvac 15W40 and a Napa Gold filter, fuel filters every 15k, and air every 30k. I told him we should start changing the tranny fluid and rear diff fluid every 50k and he agreed. I know it calls for 75W85, I was thinking of using either Redline 75W90 or 75W110, or should I stick to the 75W85? Im not sure if he has the AAM 11.5 or 12.0 axle, Ill find out. Also Id like to find the torque specs for the cover. I think its 30 lbs but some have reported bolts snapping at that torque.
You said 30 lbs. Do you mean 30 in lbs or 30 ft lbs? Actually 30 ft lbs sounds correct but a lot of people stop at 20 ft lbs and see if that’s enough to hold it with no leaks.
 
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I’m sure the Redline would be fine but I went with Delvac1 in my G80 locker a couple of years ago. I can’t remember the weight but it’s been quiet as a mouse since.
 
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Redline is hard to beat for a severe duty use like that. As far as viscosity, have you or your friend consulted the Owners Manual to see what Ram recommends for severe duty?
 
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I am lacking in the bolt terminology, the shank may be 8mm but the head is 13mm if I recall. I just did the 11.5 on my 2017 3500 the other day.

From the census on some other Ram sites, 75w90 is the oil of choice. I personally use 80w140. Not because I think it's better but I had a pile left over from another vehicle. Works fine.
 
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I am lacking in the bolt terminology, the shank may be 8mm but the head is 13mm if I recall. I just did the 11.5 on my 2017 3500 the other day.

From the census on some other Ram sites, 75w90 is the oil of choice. I personally use 80w140. Not because I think it's better but I had a pile left over from another vehicle. Works fine.
I think that 80w140 is better down to about -32C. Colder than that & not knowing the channel point, drive slow for the first few kms.
Buying 80w140 as oposed to 80w90 or 85w140 is tough on the wallet. I just bought a pail of C-Tire 80w90 on sale for a 2008 3500 Ram.
The 80w140 goes in newer 1500s & HD GMs.

Edit; I see that you shop at Co-op. I won $10 on a scratch & win and got a free coffee on Xmas day at the co-op somewhere in the middle of nowhere SK. (Around Whitewood.)
 
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I think the 80w140 has a pour point of -42C as per the PDS.

The Co-op gear oil is fully group 4. I had bought the 140 weight for the 9.25" in my 2011 1500. At 9 bucks a litre all in, it was way cheaper to get a 20L pail as opposed to a few quarts at 25$ each for Mobil, RP or Amsoil. I got two changes on the 1500, two changes on the 3500 and probably enough left over for another.
 
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I think the 80w140 has a pour point of -42C as per the PDS.

The Co-op gear oil is fully group 4. I had bought the 140 weight for the 9.25" in my 2011 1500. At 9 bucks a litre all in, it was way cheaper to get a 20L pail as opposed to a few quarts at 25$ each for Mobil, RP or Amsoil. I got two changes on the 1500, two changes on the 3500 and probably enough left over for another.
How full do you fill your diffs? I try for half an inch below the fill hole (13mm), but more often than not, running out onto the driveway.
My last 2 pails were Pet-Can and Chevron, likely Group IIIs. I think they came to around $160 taxes and enviro fees in.
 
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Per Mopar's dealer catalog there's only a 11.50. I'd do amsoil or redline in 75w110 or 75w140.

Also FYI that truck should be using a syn 5w40 or 10w30. In older models 15w40 is ok but Chrysler had sent my dealer a notice with pictures of turbos and I believe EGR's showing the build up from consistent conventional 15w40s.
 
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I am lacking in the bolt terminology, the shank may be 8mm but the head is 13mm if I recall. I just did the 11.5 on my 2017 3500 the other day.

From the census on some other Ram sites, 75w90 is the oil of choice. I personally use 80w140. Not because I think it's better but I had a pile left over from another vehicle. Works fine.
Yes, bolt size is measured from the outside of the tread to the outside of the thread directly across, hence it is a 8 mm bolt but in this case requires a 13 mm wrench to tighten it.

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I’ve used Valvoline 75w-90 and 22lbs. on diff cover filled a knuckle below fill Hole. truck runs fine towing about 10,000lbs a few times a year. With his heavy towing I recommend a brake fluid flush and bleed; 2 quarts of dot3 should do it. Also a good trick to oil filter removal is to stretch a rubber disposable glove over filter before tilting and pulling thru wheel well, no spills here!
 
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