Dodge2500 pulling 4,000 Lb trailer with M 1 75W-90

[24 VALVE]

I changed out the front and rear diff fluild in my 02 Dodge
Cummins 2500 auto trans, Dana 70 rear and Dana 60 front
with what was back then the #@$%! of diff fluids, Mobil 1
75W-90.

Huge debates on Turbodieselregister and dodgetruck/world
raged day and nite on which to use: 75W-90 or Dodge's recommendations of 75W-140 if you tow with your truck.

The most interesting posts that really got my attention was from a technician at Eaton, where he claimed Eaton recommends and will only warranty their rear diffs in over the road trucks if they run M1 75W-90, and that is with those trucks grossing up to 80,000 pounds.

So I used M1 75W-90. All I can offer you in all this ramble, is that after 33,000 miles of my Dodge pulling at the most a 4,000 pound RV trailer (Aerolite), I changed it
out and there was absolutely such a small amount of metal stuck to the drain plug magnet, that is not even worth mentioning. And fluid still looked pretty good, dark, but not even close to black. I do run the Mag-Hytec extra capacity rear cover.

Also, when I carried the drain pan out from under the truck, in the bright sunshine, there was zero metal in the oil as far as the sun shining off metal particles in the oil. I was impressed.

But I got concerned about M1 75W-90 having a 15 weight at
100C so I went to Royal Purple 75W-90 which is about 20 weight at 100C, a little more protection without going to the 140 weight. If I was pulling 6,000 or more I think I would use the 75W-140.

Thanks for reading!

 

[JHZR2]

M1 75w-90 is great stuff. In fact, all the real syn diff oils, M1, redline, RP, amsoil, are super high qality, and likely protect better than an el cheapo 75w-140 would.

There was a great documentation at mercedesshop, where a guy with a 300D opened his diff, and saw it dirty inside, after regular changes of conventional diff oil. He put M1 in there for 15000 miles or so, and you could see metal in there after he took it apart again... It is good stuff, and I use it with confidence.

If eaton wants 75w-90 for their warranty, and this includes 80k lb trucks, then you certainly can trust it in your setup, since you have extra capacity.

Good luck!

JMH

 

[SteveD2]

While it might be fine in your dana axle (they tend to be easy on fluid), I burnt a fill of M1 75w90 in my 04.5's AAM axles...and that was with zero towing and in less than 25k miles. The oil that went in clear, drained brown and felt thin. The rear diff was making so much noise, it sounded like the pinion bearings had failed. I replaced the M1 with RP 85w140 and immediately the noise was gone. And as a bonus, I picked up some mileage (even going to the slightly heavier weight oil).

With that said (as a disclaimer that M1 isn't a great choice for every application), I ran conventional 75w140 in my D70 in my 99 and never had any issues in over 200k of driving (including several towings exceeding 10k). As I said before, the Dana axles tend to be easy on fluid...

steved

 

[oil pan 4]

I have towed a 6,000lb trailer up to 1,000 at a time with my suburban with a rear full of dino 75w-90 weight "bulk" brand gear oil. My truck has a GM 10 bolt.
I checked the rear before I was going to tow, I was away form home so I could not change it. So I pulled the fill plug and the oil was black. So I figured I would take it some where and get it changed. Because it would be better off with new 75w-90 from the 1 gallon jug then what was in there at the time.
I am going to change it to Mobil 1 75w-90 before my next long haul.

 

[Pablo]

Honestly Amsoil had this is mind when they came out with the 75W-110:
Amsoil Severe Gear 75W-110

 

[Steve S]

With all the experts who think they know , I will tell you an unknown secret.The Cummins,the Powerstroke and the Duramax engines put out lots of torque instantly, which is a shock loading on the gears in the differential gears in a quite small for the torque differental The 80w/140 oil provides a better "cushion " between the gears. You can not compare what goes in a semis rear end as the use of the unit will tell what viscosity oil is required. Besides semi truck rear ends are optioned for the weight and the torque needed.

 

[1sttruck]

The OEM fluid at 15k miles in both AAM axles of my 2003 Dodge looked like black snot. I don't tow anything. I think that someone found that he OEM fluid was a Texaco product. I changed with M1 75W90 and at 30k it looked like a darker olive oil. I put M1 75W140 in and at 60k miles it again looked like a darker olive oil, no metal flakes, just a light gray film on parts of the axles. I put M1 75W90 back in and have the impression that there is less rolling friction. So far it's as quiet as the 75W140, and I'll see what summer temps do before deciding what to do next, like maybe 75W90 in the front axle and 75W140 in the rear.

 

[1040 WreckerMan]

You cannot really compare the Eaton big truck diffs to the smaller ones found in pickups. First of all, the pinion to ring gear offset is completely different. Also, big truck diffs typically have other stuff going on inside them such as axle locks, diff lock (for tandem or tri-drive units) and the power divider(s) (for tandem and tri-drive). Eaton does usually require a 85w90 oil, however their requirements are based on temperature. They do require the oil to meet certain specifications depending on whether the drive axle is over the road, off-road, vocational, etc. At work, all of the trucks that have Eaton diffs need to run 75w140 or 85w140. In some cases the requirements are also based on the size and options of the diff. Many Eaton diffs have lube pumps to positively pressure lube components, in which case a lighter gear lube can be used.

I like thicker oils for just about any gear setup. The thicker oil helps to protect against shock loads among other properties. With anything other than an econobox, gear oil weight does not have a big impact on power output or fuel economy, so their really isn't any reason to run a lighter gear oil other than temperature considerations. Certainly in any diesel powered pickup and I would run 140wt. A linehaul tractor that never sees more than 34,000lbs on the drive axles (max legal weight in most states without permitting) have 36/38k lbs axles and do nothing but drive up and down the freeway. They can get away with a lighter gear lube, especially when they have pressure lube systems in place. I would rather sacrifice a .00000000001%

drop in fuel economy for the piece of mind that I'll not have to dig into the diffs in the near future.

I've done enough diff repairs in the field to know I don't like them. When we tried running a lighter gear oil in some of the trucks our failure rate went through the roof (comparatively), and I don't like pulling diffs on the rear drive axle at 4000ft in the snow

.

Some axles can be run on lighter oil, but it depends on design and usage as to how well it will work. Some axles have higher hypoid angles than others, which plays into oil life at a given viscosity. Also, the size of the ring gear/pinion and bearings for input torque and load have a profound impact on oil and component life at a given viscosity.

 

[1sttruck]

I put 75W140 in at one change as supposedly a TSB had been issued to use it for 'severe duty' in the newer Dodge axles. But the TSB has never turned up, and people calling AAM seem to get consistent reommendations to use 75W90, while a few Dodge dealers will recommend 75W140. The manual says to use 75W90.

Dodge specs 75W90 with a 15k mile change, which is pretty short. One would think that they'd recommend 75W140 if it provided lower wear, but perhaps foaming is an issue ?

 

[Colt45ws]

the 2003 dodge ram FSM I have says 75W140 in 9 1/4(?) rear diffys while everything else, including 9 1/4 fronts are to get 75W90.

 

[1040 WreckerMan]

There maybe some CAFE concerns playing into this equation since the service manual is directed toward pickups rather than a commercial truck where fuel economy isn't as important. Dodge and AAM maybe thinking along the lines that the larger diffs have significant increases in surface area so a lighter weight oil will carry the load with acceptable results. This doesn't mean the factory recommendation can't be improved upon.

It's also possible that the axles were designed specifically to run 75w90. Also consider that AAM has been around for a while and they have been building diffs (and other driveline components) for the industrial market for a while. I don't think that the axles used in Dodge and GM pickups were built for said brand specifically, but rather were an adaptation of an existing design. I think, but could be mistaken, that the Dodge rear drive axle is an AAM 1150 in Salisbury/cast iron and is compatible with a number of different lube choices.

 

[1sttruck]

The 3/4 and 1 ton trucks don't have CAFE concerns as the GVW exceeds the cutoff. The 3/4 and 1 ton vehicles also MUST be durable, considering that they are often purchased for towing, so it doesn't make sense to sacrifice durability for fuel economy when there is no CAFE fuel economy pressure. Most of the diesels have the 11.5in rear axle, mine is, while some have a 10.5in. The 9.25 is used up front.

 

[SteveD2]

Quote:

---

The 3/4 and 1 ton trucks don't have CAFE concerns as the GVW exceeds the cutoff.

---

Don't you believe it...

I think it comes down to simply this:

Just like auto trans fluid, DC wants ONE gear oil for all. The 47RE and 48RE autos do not need ATF+4 which was designed for the FWD, but they will tolerated it. And to keep low stock of oils on hand, they simply used the most common weight whether it is 100% correct or not...as long as the particular component using it will survive to 70k (the norm warranty), that's all they care. If they can keep two engine oils (5w30 gas and 15w40 diesel), one auto transmission fluid (ATF+4), one manual transmission fluid (now ATF+4), and one differential gear oil (75w90) on hand, there is less chance of THEM installing the wrong oil in your car/truck and less storage and stock to keep on hand at any one time.

And CAFE, while it doesn't need to be posted on the 2500/3500 trucks, STILL APPLIES in the overall "fleet's" CAFE number...why do you think the PT Cruiser is registered as a truck???? To bring the overall CAFE number of the dodge trucks up!!!

Another thing...the Corp 9.25 rear is an Eaton IIRC, while the 9.25AAM front is obviously an AAM. And the 9.25AAM is very close to the 9.25AAM differential used in the 2500/3500 GM IFS.

I would be curious to see what the GM boys are spec'd for gear oil weight in their 11.50AAM (slightly different 11.50 AAM from the dodge version, but should be close enough)...I think I will post this question on the diesel boards (more exposure to those types of trucks).

steved

 

[rt_ponder]

How about a straight 140wt or a 85/140 gear oil, stop all the guess work. Looks like this rig gets worked pretty hard, put some lube that is up to those kinds of pressures and heat. Obviously, the mobil 1 aint hacking it.

 

[unDummy]

Because of your extra capacity cover, you don't need the 140wt. The added capacity and cooling are protecting your 'end.
But, I will always recommend a 140wt, over the 90wt, when a vehicle is worked weather plowing, towing, hauling...... simple because I've seen the wear difference. Thick oil protects! Since Dodge recommends the 140wt for towing, I'd definitely consider it.

Individual MPG loss, because of thicker fluids, is meaningless. But, when accounting for 100's of thousands of yearly sales, the automaker likes that miniscule assistance with CAFE.

For those of you that don't want to offend the owners manual requiring lighter weights, the RP Maxgear is one of the thicker 75w90's. You could also do a 50:50 blend with 90 and 140wt gear oils. Amsoil and Gibbs have 75w110's gear lubes available now. There are also some SAE90's that are pretty thick. If you don't have extreme cold weather, SAE90's are worth looking into.

I also don't see where the M1 isn't hacking it. Did I miss something in the original post?

 

[1sttruck]

http://www.nhtsa.dot.gov/cars/rules/cafe/overview.htm

Are any vehicles exempted from CAFE standards?

Light trucks that exceed 8,500 lbs gross vehicle weight rating (GVWR) do not have to comply with CAFE standards. These vehicles include pickup trucks, sport utility vehicles and large vans.

A study prepared for the Department of Energy, in February 2002, by the Oak Ridge National Laboratory found that 521,000 trucks with GVWR from 8,500 to 10,000 lbs were sold in calendar year 1999. The vast majority (82%) of these trucks are pickups and a significant number (24%) were diesel. At the end of 1999, there were 5.8 million of these trucks on the road accounting for 8% of the annual miles driven by light trucks, and 9% of light truck fuel use.



How is a manufacturer’s CAFE determined for a given model year?

A manufacturer’s CAFE is the fleet wide average fuel economy. Separate CAFE calculations are made for up to three potential fleets: domestic passenger cars, imported passenger cars and light trucks. The averaging method used is referred to as a “harmonic mean”. The regulatory language describes the calculation as: “the number of passenger automobiles manufactured by the manufacturer in a model year; divided by the sum of the fractions obtained by dividing the number of passenger automobiles of each model manufactured by the manufacturer in that model year by the fuel economy measured for that model.” The numerical example below illustrates the process. Assume that a hypothetical manufacturer produces four light truck models in 2004, where MPG means miles per gallon and GVWR means gross vehicle weight rating measured in lbs:

Model MPG GVWR Production Volume
Vehicle A 22 3000 130,000
Vehicle B 20 3500 120,000
Vehicle C 16 4000 100,000
Vehicle D 10 8900 40,000

Because the Vehicle D exceeds 8,500 GVWR, it is excluded from the calculation.

 

[1040 WreckerMan]

Regardless of CAFE or any other consideration, thicker is better for gears. There are certainly some items such as ambient temps to consider, however is most places in the world thicker is better. With 100's of millions miles of field testing I feel confident recommending thicker gear oils, especially for a truck that won't care about a few cSt increase as far as power or mileage is concerned.

 

[SteveD2]

Quote:

---

http://www.nhtsa.dot.gov/cars/rules/cafe/overview.htm

Are any vehicles exempted from CAFE standards?

Light trucks that exceed 8,500 lbs gross vehicle weight rating (GVWR) do not have to comply with CAFE standards. These vehicles include pickup trucks, sport utility vehicles and large vans.

A study prepared for the Department of Energy, in February 2002, by the Oak Ridge National Laboratory found that 521,000 trucks with GVWR from 8,500 to 10,000 lbs were sold in calendar year 1999. The vast majority (82%) of these trucks are pickups and a significant number (24%) were diesel. At the end of 1999, there were 5.8 million of these trucks on the road accounting for 8% of the annual miles driven by light trucks, and 9% of light truck fuel use.



How is a manufacturer’s CAFE determined for a given model year?

A manufacturer’s CAFE is the fleet wide average fuel economy. Separate CAFE calculations are made for up to three potential fleets: domestic passenger cars, imported passenger cars and light trucks. The averaging method used is referred to as a “harmonic mean”. The regulatory language describes the calculation as: “the number of passenger automobiles manufactured by the manufacturer in a model year; divided by the sum of the fractions obtained by dividing the number of passenger automobiles of each model manufactured by the manufacturer in that model year by the fuel economy measured for that model.” The numerical example below illustrates the process. Assume that a hypothetical manufacturer produces four light truck models in 2004, where MPG means miles per gallon and GVWR means gross vehicle weight rating measured in lbs:

Model MPG GVWR Production Volume
Vehicle A 22 3000 130,000
Vehicle B 20 3500 120,000
Vehicle C 16 4000 100,000
Vehicle D 10 8900 40,000

Because the Vehicle D exceeds 8,500 GVWR, it is excluded from the calculation.

---

If you read into this a little further, you'll find this is Commercial vehicles.

But I'm not going to argue...I've already had this discussion.

steved

 

[1sttruck]

There is no distinction made between 'commercial' or personal vehicles, instead the distinction is gross vehicle weight.

http://www.nhtsa.dot.gov/cars/rules/cafe/overview.htm

What is CAFE?
Corporate Average Fuel Economy (CAFE) is the sales weighted average fuel economy, expressed in miles per gallon (mpg), of a manufacturer’s fleet of passenger cars or light trucks with a gross vehicle weight rating (GVWR) of 8,500 lbs. or less, manufactured for sale in the United States, for any given model year. Fuel economy is defined as the average mileage traveled by an automobile per gallon of gasoline (or equivalent amount of other fuel) consumed as measured in accordance with the testing and evaluation protocol set forth by the Environmental Protection Agency (EPA).

 

[TheTanSedan]

Just changed the fluid in a (new-to-me) 2004 DODGE Ram CTD. With 122,000+ miles the fluid level was low and the wear was next to non-existent on this AAM gearset. The previous owner was loading the bed and pulling a small trailer (under 5,000). As I can get near-to-wholesale pricing on DCX stuff I went with the MOPAR replacement fluid. I know that the fluid had never been changed previously and this gave me no reason to change (in other vehicles I use REDLINE and/or SCHAEFFERS exclusively).

As to -140 oil it's hard to see a reason to change. I'll be using this truck with an 8,000-lb trailer and occasional heavy bed loads. I'll change again at 140,000 or so. I really think AAM has their act together (unless others can direct me to numerous problems . . I don't see it on the different boards).