2017 Ram 1500 3.92 LSD Fluid

[Hsargent21]

So I went to my dealership today to get fluids for the transfer case, front and rear differentials. The fluid that they gave me for the front differential and the transfer case match what the owner’s manual call for. However the owners manual calls for SAE 75W - 140 and 5 ozs of LSD additive for the rear diff. They looked up my vin and told me that the rear diff on my particular truck calls for SAE 75W - 90 and none of the additive. So who do I trust. The owners manual or the dealerships computer? This vehicle has a lifetime warranty that I don’t want to loose. Anybody have this issue?

 

[Ridgerunner665]

Are you absolutely sure you have the limited slip?

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[Hsargent21]

Yes. At least that is what I ordered and was on the window sticker. The dealership that I bought the fluid at also confirmed that it was a LSD but didn’t require the additive

 

[Burla]

All modern synthetics have lsd additive in there, don't get any more, and your rear takes 75 w140 because it is 1500, the 2500's and up take the lighter 90 weight. You need a boutique oil to order synthetic w/o additive, it is all one size fits all.

 

[Burla]

This oil is pretty popular around here. Do not get the version that says NS in title, that is for old gear boxes. As you see it is for ram and has modifiers in there. Nick at gotexhaust sells it cheaper then this listed price.

• Popular for cars and light trucks like Ford Mustang and F-150, Toyota Tundra and Sequoia, Jeep Cherokee and Dodge Ram
• Contains additional friction modifiers for suitability with clutch-type limited slip differentials - for most LSDs, no additional friction modifiers are required

 

[Burla]

If you get that you need a slippery pete pump from amazon, match it to quarts or gallons of that is what you order. Or get severe gear fluid from amsoil, they have squeeze bags no pump needed.

 

[Hsargent21]

I contacted a second dealership and the confirmed that the book is wrong...my rear diff calls for 75W-90.

 

[Burla]

You know I would ask specifically why they are saying that, every 4 gen ram 1500 takes 140w oil, I would ask why exactly they want to put the thinner oil in your diff, as in which diff do they say you have via vin number. 5th gens have mechanically heated diifs, which is even worse as far as user thinner oil, but you have 4th gen yes?

 

[GIJoe2010]

BOOM!!!

Straight outta the manual.

 

[Hsargent21]

Burla...yes it is a 4th Gen

GiJoe...yep...my book shows the same thing and I showed it to them. I will check with another dealer in the AM.

 

[MRFREEZE57]

changed mine with redline 75-140, did not use the additive as redline says has additive for LSD applications, has been ok as far as can tell.

 

[ram1500rsm]

What if Mopar issued a revision? Lol
Op don't over stress too much about what the dealer is telling you. You don't even need to show them the vin the part number for the fluid is listed in the book. Tell them you want 3 bottles of that stuff an the FM.

I went even easier and picked my fluids from AutoZone. For the back I went with 3 bottles of Valvoline powerSyn 75w140 and that has FM already. The diff took 2.5 bottles. I have 3.92's with LSD. Zero issues since I did the change last year.

 

[Hootbro]

Something changed for whatever reason in 2017 in FCA calling out 75W-90 for the rear diff. My online PDF copy owners manual for my 2017 1500 calls out using 75W-90.

 

[GIJoe2010]

Weird

 

[Hsargent21]

I looked on the Mopar site for my vehicle. There is two different links to the owners manual. One shows 75-80 and the other shows 75-140. Both with LSD addictive. Two dealerships say no additive. I sent a message to Ramcares to see what they say. Either way I’m waiting on a 14mm Hex...lets go Amazon.

 

[ram1500rsm]

Yep prob some MPG to be gained with the lighter weight fluid. It can't be bad when our big brothers can tow way heavier and they run 70w90. Lol. it seems the manuals were revised in 2017 and up. Same diff as far as I know. But Mopar now says 70w90 is fine for your rear diff. Lighter diff fluid should give you more mpg and possibly free up some ponies. If you don't tow heavy I don't think there should be any issues changing it. I used the heavy one cause I offroad often plus I have the factory clutch based LSD. Clutches run hotter compared to an open diff.
I think Amsoil makes a 75w110 that I guess could serve as heavy duty fluid and MPG helper. Just to throw another option for the op.

 

[stenerson]

Ouch! I changed mine last month and assumed it took 140.... Sounds to me like either works fine for casual driving.

 

[Hsargent21]

I heard back from RamCares...my rear diff does call for 70-90. Now waiting for them to tell me if it needs LSD additive. The dealership said it didn’t

 

[ChevySlayer69]

Well this thread surprised me. I use Valvoline 75w140 and change it annually. I dont plan on using a thinner fluid for 0.1 mpg.

 

[stenerson]

Well this thread surprised me. I use Valvoline 75w140 and change it annually. I dont plan on using a thinner fluid for 0.1 mpg.

Well this thread surprised me. I use Valvoline 75w140 and change it annually. I dont plan on using a thinner fluid for 0.1 mpg.

Yep, I'll stick with 140. I doubt there's any change to the diff itself that warrants a change in fluid spec.