Differential Oil for Off Road use and Hot Climate

[knightjp]

@HEMIMANN For the most of the time I am driving empty. We face 50.C weather for about 4 months in the year.
I drive 100kms daily, mostly at highway speeds and drive off road on dunes and dirt trails on the weekend.

 

[HEMIMANN]

@HEMIMANN For the most of the time I am driving empty. We face 50.C weather for about 4 months in the year.
I drive 100kms daily, mostly at highway speeds and drive off road on dunes and dirt trails on the weekend.

I guess stay with owners manual recommendation, I didn't know you couldn't get a Banks Cool Cover with a half ton model.

I will say I've never had an issue with synthetic oils in any kind of gearboxes. In fact, the more severe the machine element motions are sliding, the cooler the gears stay using synthetic. Also some small fuel savings, and less oxidation and deposits.

What I remember for type of gear with most power loss and heat build up:

1. Worm Gear Sets
2. Hypoid Gear Sets
3. Spiral Bevel Gear Sets
4. Helical Gear Sets
5. Spur Gear Sets.

Worm gears are awful - only ~ 60% efficient in mechanical power transfer, 40% lost to frictional heat. With Mobil, we worked with Coal Fired Power Plants to use synthetic oil in their 400 gallon worm gear boxes driving coal pulverizer balls. In order to justify the purchase cost, they had to install a 1 psi air pressure spigot to the box to keep the coal dust from getting past the pulverizer seals into the oil. They were changing oil every month. I think they ended up not changing for a year, and also used 3-4% less electricity in the motor.

 

[Gr8bawana]

I seriously doubt you would ever notice any difference if you used conventional gear oil or synthetic gear oil.
There are millions upon millions of old cars and trucks out there that have been driven hundreds of thousands of miles and never had anything other than conventional gear oil.

 

[Curmudgeon]

Yep, but I want to get 500,000 miles from my rig, because years ago you could get a nice 4x4 fully loaded for about $8k-10k, and now I'm retired and just so happen to really really like my '14 Laramie.

Now I just want to do all I can to protect my paid-for "investment" and if that means spending a couple dollars more to get a superior product in it, I'm all in.

Until i bought a new car in 2001 (2000 Chrysler Concorde LXi) and pulled 100% synthetic OCIs I never had any vehicle last over 109k miles before major repairs were required.

That LXi ran flawless for 190,000 miles until my drunk brother snatched the keys and wrapped it around a utility pole. *******.

Same with my 2008 Civic which gave me 248,000 miles before I bought my Ram, and sold the Civic to some kid who riced it up and sold it again for a profit. I keep tabs via FaceBook, that little **** is STILL out there.

Everything got beat like a rented mule, but only the ones that got my best attention and upkeep gave me a good 5 years payment free and trouble free. All anecdotal BS of course, but it makes sense to me, and has worked for me so far.

 

[knightjp]

@Curmudgeon Fo keeping a vehicle that long, nothing like a good maintenance schedule. Of course you need to watch out for the ZF 8 speed issue and fix that. Honestly the ZF is the best box IMO once you preemptively fix that issue. Even in its broken state, it kept on going. Other boxes would have given up considering what I put it through. When it comes to the idea of reliability, Most expect only Toyotas to last forever. Guess what, they don’t. Maybe at one time they did, but these days, IMO, they’re just another brand and will sell you inferior quality at double the cost, just because they know they have that reputation and people will buy it.
Rant over, we’ve got the same goal. IMO just keep up with the maintenance. Change the oils on time and keep on going.
Engine - every 5000 kms
Gearbox - every 40k kms
Transfer - every 40k kms
Differentials - every 20k kms.

 

[Curmudgeon]

I'm miles-based, so OCIs are 5k miles, 8-speed trans is 80k miles, very light duty, both diffs and transfer case are done every 30k miles.

Engine and drive train just done last week, 8-speed probably again in a couple years. I average 6k-7k miles per year now. Odometer is right around 121,600.

Everything is original (except brakes/tires/battery) except fluids, even brake and coolant, all replaced on time or before. Only exhaust manifolds and fuel level sensor have had to be replaced.

 

[Wild one]

@Curmudgeon Fo keeping a vehicle that long, nothing like a good maintenance schedule. Of course you need to watch out for the ZF 8 speed issue and fix that. Honestly the ZF is the best box IMO once you preemptively fix that issue. Even in its broken state, it kept on going. Other boxes would have given up considering what I put it through. When it comes to the idea of reliability, Most expect only Toyotas to last forever. Guess what, they don’t. Maybe at one time they did, but these days, IMO, they’re just another brand and will sell you inferior quality at double the cost, just because they know they have that reputation and people will buy it.
Rant over, we’ve got the same goal. IMO just keep up with the maintenance. Change the oils on time and keep on going.
Engine - every 5000 kms
Gearbox - every 40k kms
Transfer - every 40k kms
Differentials - every 20k kms.

If you're changing the diff fluid every 12,500 miles,i highly doubt you'd notice any life expectancy differance between synthetic or mineral based gear fluids except how much lighter your wallet will be by using synthetic.
If you don't have an infared thermometer,spring for one and use it to check your diffs actual temperature after a decently long high speed run on a hot day.That'll give you an idea of how hot your diff fluid will be getting

 

[Grams]

I live in the Middle East where the temps during Summer average 50.C
I'm told by ChatGPT that the standard differential oil for my 2014 Ram 1500 is:
SAE 75W-85 GL-5 in the front
SAE 75W-140 GL-5 in the rear (Mopar spec MS-8995).
I'm sure that I can get the original Mopar brand oil, however I was wondering if there were any tips in terms of oil brand, viscosity and change intervals; especially for those who live in my kind of climate.

For instance, brands like Valvoline over here only stock 80W-90 and 85W-140. Are these also acceptable?

How often should the diff oil be changed?

Yes, IMO, they are acceptable in warmer-climates, … and the OCI recommended by mfr’r should be maintained.

(But, if the mfr’r ships the vehicle to your climate with the oil specified when new…. Why would it be necessary or wise to make such a change?)

 

[Wild one]

Yes, IMO, they are acceptable in warmer-climates, … and the OCI recommended by mfr’r should be maintained.

(But, if the mfr’r ships the vehicle to your climate with the oil specified when new…. Why would it be necessary or wise to make such a change?)

Mopar doesn't buy fluid based on life expectancy,they buy fluid based on the lowest bidder.They send the specs out for bid,and the very bottom bidder who meets the bare mininium specs gets the fluid contract.Generally most of the fluids used by Ma Mopar have the nickname "Unicorn P!ss",and there's a reason why they've got that nickname,it sure as hell isn't because they're using the best quality of fluids,it's because they're using the cheapest fluid they can get their hands on

 

[HEMIMANN]

Mopar doesn't buy fluid based on life expectancy,they buy fluid based on the lowest bidder.They send the specs out for bid,and the very bottom bidder who meets the bare mininium specs gets the fluid contract.Generally most of the fluids used by Ma Mopar have the nickname "Unicorn P!ss",and there's a reason why they've got that nickname,it sure as hell isn't because they're using the best quality of fluids,it's because they're using the cheapest fluid they can get their hands on

I can vouch for that. It's why Cummins Power Generation rarely won spec & bid business Rfq's, and didnt respond to many except for the few serious projects that engineers specs quality requirements that junk providers couldn't deliver. At a higher cost and price.

Any wonder why we don't go to Dealers or Quickie Lube Joints?
Find a quality local Indie Shop, except for warranty work. And even then sometimes. Look at the trouble members have had with the CP4 diesel pump and ABS recalls!

 

[knightjp]

Mopar doesn't buy fluid based on life expectancy,they buy fluid based on the lowest bidder.They send the specs out for bid,and the very bottom bidder who meets the bare mininium specs gets the fluid contract.Generally most of the fluids used by Ma Mopar have the nickname "Unicorn P!ss",and there's a reason why they've got that nickname,it sure as hell isn't because they're using the best quality of fluids,it's because they're using the cheapest fluid they can get their hands on

When querying on what oil to use in my gearbox, on this very same forum I found a thread that said the Mopar oil spec'd for the 8 speed was one of the best to use.
What is said above can be said about all vehicle brands these days. Everyone is trying to cut cost as much as possible and increase profits. This is the dark side of capitalism, but I'd rather this than socialism or worse, democratic socialism.

 

[murderman]

Personally, I never understood the 140 viscosity spec for the rear differential for a light duty truck. 140 is normally reserved for heavy duty that tows. Maybe someone will chime in that knows what Ram was up to way back when.

Anyway, yes you are in 50C 122F area, hot ambient for any machine element. Beyond what I said above, how do you use your truck? Do you drive empty all the time? Most of the time? If you load or tow, do you load/tow heavy or little? How often do you drive in 50C 122F?

These answers determine how to spec viscosity. In terms of brands, past study data presented here showed Amsoil #1 and Mobil 1 #2 in performance test metrics. Personally I use Mobil Delvac 1 75W-90, as it has no limited slip friction modifier additive (one of the few that doesn't) because I have the AAM TracRite Torsen all gear differential that has no clutch packs. This auto-locking differential doesn't like friction modifiers - it delays locking.

The Torsen differential is most definitely not "auto-locking" like a Detroit or Grizzly, it is a gear-type LSD and not a locker at all.

 

[Wild one]

When querying on what oil to use in my gearbox, on this very same forum I found a thread that said the Mopar oil spec'd for the 8 speed was one of the best to use.
What is said above can be said about all vehicle brands these days. Everyone is trying to cut cost as much as possible and increase profits. This is the dark side of capitalism, but I'd rather this than socialism or worse, democratic socialism.

The 8 speed fluid is not spec'd by Mopar,it's spec'd by ZF . Ma Mopar buys the transmissions already pre-filled from ZF,except for the little 854E ,which Mopar builds under licence from ZF

 

[HEMIMANN]

The Torsen differential is most definitely not "auto-locking" like a Detroit or Grizzly, it is a gear-type LSD and not a locker at all.

Uh, wut?

Show me the electronic actuator, please.

 

[Daniel J]

I guess stay with owners manual recommendation, I didn't know you couldn't get a Banks Cool Cover with a half ton model.

I will say I've never had an issue with synthetic oils in any kind of gearboxes. In fact, the more severe the machine element motions are sliding, the cooler the gears stay using synthetic. Also some small fuel savings, and less oxidation and deposits.

What I remember for type of gear with most power loss and heat build up:

1. Worm Gear Sets
2. Hypoid Gear Sets
3. Spiral Bevel Gear Sets
4. Helical Gear Sets
5. Spur Gear Sets.

Worm gears are awful - only ~ 60% efficient in mechanical power transfer, 40% lost to frictional heat. With Mobil, we worked with Coal Fired Power Plants to use synthetic oil in their 400 gallon worm gear boxes driving coal pulverizer balls. In order to justify the purchase cost, they had to install a 1 psi air pressure spigot to the box to keep the coal dust from getting past the pulverizer seals into the oil. They were changing oil every month. I think they ended up not changing for a year, and also used 3-4% less electricity in the motor.

 

[Wild one]

The Torsen differential is most definitely not "auto-locking" like a Detroit or Grizzly, it is a gear-type LSD and not a locker at all.

Are you sure you're not thinking of the ARB air or electric lockers

 

[Grams]

Mopar doesn't buy fluid based on life expectancy,they buy fluid based on the lowest bidder.They send the specs out for bid,and the very bottom bidder who meets the bare mininium specs gets the fluid contract.Generally most of the fluids used by Ma Mopar have the nickname "Unicorn P!ss",and there's a reason why they've got that nickname,it sure as hell isn't because they're using the best quality of fluids,it's because they're using the cheapest fluid they can get their hands on

That is contradictory if you think about. it .

If Mopar issues a “request for quote” for gear-oils meeting a certain specification…. Then whatever supplier meets that spec at the best price…is who Mopar will likely select…. EXACTLY the SAME THING you and I both do.

If it meets the spec…. it’s appropriate for use.
If it’s acquired at a favorable price….that’s Not a Detriment…it’s a Bonus!

Furthermore, if Mopar supplies the product under their own brand-name…then there’s no argument about whether it meets the requirements for warranty coverage. Easy choice.

 

[Wild one]

That is contradictory if you think about. it .

If Mopar issues a “request for quote” for gear-oils meeting a certain specification…. Then whatever supplier meets that spec at the best price…is who Mopar will likely select…. EXACTLY the SAME THING you and I both do.

If it meets the spec…. it’s appropriate for use.
If it’s acquired at a favorable price….that’s Not a Detriment…it’s a Bonus!

Furthermore, if Mopar supplies the product under their own brand-name…then there’s no argument about whether it meets the requirements for warranty coverage. Easy choice.

So you'd rather use fluids that just barely meet the mininium spec,then a fluid that well exceeds the manufacture's specs.Well you can do you ,but me i'll stick to using fluids that are better quality then what Mopar fluids generally are.The caveat being the fluid for the 8 speeds,which is not spec'd by Ma Mopar,but is spec'd by ZF.
Ever wonder why Mopar changes called for oil manufacture's as often as they do,it's cause they grind their suppliers to the point the good ones tell them where to go

 

[Grams]

So you'd rather use fluids that just barely meet the mininium spec,then a fluid that well exceeds the manufacture's specs.Well you can do you ,but me i'll stick to using fluids that are better quality then what Mopar fluids generally are.The caveat being the fluid for the 8 speeds,which is not spec'd by Ma Mopar,but is spec'd by ZF.
Ever wonder why Mopar changes called for oil manufacture's as often as they do,it's cause they grind their suppliers to the point the good ones tell them where to go

Do you buy 91 octane fuel when your vehicle only calls for 87…?

People who do that may FEEL GOOD about their choice…. but it’s only a “feeling”…. does nothing for the vehicle.

Refiners who make product that meet OEM “specifications” …don’t make a product that “barely” meets it. In almost every instance, They make an industry-standard (ILSAC/SAE/ETC) that meets and exceeds.

What the Mopar dealership sells for Mopar differentials is fine, regardless of where in the world it’s sold. IMO

<edit> BTW…last rear diff oil change…my favorite shop used a Valvoline product that met Mopar spec.. and I’m OK with that too. No need for excess worry over this kind of thing, IMO.

 

[Wild one]

Do you buy 91 octane fuel when your vehicle only calls for 87…?

People who do that may FEEL GOOD about their choice…. but it’s only a “feeling”…. does nothing for the vehicle.

Refiners who make product that meet OEM “specifications” …don’t make a product that “barely” meets it. In almost every instance, They make an industry-standard (ILSAC/SAE/ETC) that meets and exceeds.

What the Mopar dealership sells for Mopar differentials is fine, regardless of where in the world it’s sold. IMO

<edit> BTW…last rear diff oil change…my favorite shop used a Valvoline product that met Mopar spec.. and I’m OK with that too. No need for excess worry over this kind of thing, IMO.

I don't own anything that calls for 87,neither does your 5.7 truck,it reconmends 89,says you can use 87 if you're cheap,but the reconmended fuel is 89. I've found even my 300 runs better and gets better milege on 91 then it does on the reconmended 89,the rest of my old toys all ran on 94 with both the truck and wifes 1320 running MS109 in their seperate stand alone fuel cells.
You're dreaming if you think the suppliers are exceeding the mininium requirements Mopar sends out for bid,they wouldn't get the contract,as their prices would have to increase to exceed the mininium specs.