2020 1500 3.92 diff fluid. ?

[jc312]

Trying to figure out what diff fluid I need to service with. It has 3.92 ratio and the axle lock feature. Unsure about limited slip tho...

Tried several times this morning to pull up a build sheet using my vin, and I'm sure Im typing it in correctly, but nothing ever pulls up...

Are locking axles by definition not limited slip? Or is there any other way to find out? Thanks

 

[BowDown]

You mean e-lockers? No, they are open until locked but I doubt using a LS additive would harm it

 

[jc312]

Its got an "axle lock" button, that locks both rear wheels aka positive traction.. I think is the word.

But also has traction control, and another button to disable that

Seems I read a year or so ago that having the axle lock button means its not limited slip. ?

 

[Ramintime]

Its got an "axle lock" button, that locks both rear wheels aka positive traction.. I think is the word.

But also has traction control, and another button to disable that

Seems I read a year or so ago that having the axle lock button means its not limited slip. ?

Correct, you do not need the additive as the locker is different from the LSD. You could put in a additive as it won't hurt or help anything. Just go by the oil weight of what the manual says, most gear oil already has a small amount of fiction modifier in it anyway.

 

[jc312]

Correct, you do not need the additive as the locker is different from the LSD. You could put in a additive as it won't hurt or help anything. Just go by the oil weight of what the manual says, most gear oil already has a small amount of fiction modifier in it anyway.

Appreciate the reply. I still wish I was 100% sure. I guess at this point I'm around 98-99% lol

So if I turned off traction control and got on a dirt road and stomped it, there would be two spin marks if it had limited slip? Or would somehow not spin

And only one spin mark if it wasnt... ?

Something else I just read is you can jack up the rear of the truck and spin one tire. If the other spins the same direction, its limited slip.

Im just a little nervous about possibly messing something up. I guess the easy thing would be to just add the friction modifier and forget about it. But would still just like to know what the heck Ive got

 

[PurpleRT]

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[BowDown]

Appreciate the reply. I still wish I was 100% sure. I guess at this point I'm around 98-99% lol

So if I turned off traction control and got on a dirt road and stomped it, there would be two spin marks if it had limited slip? Or would somehow not spin

And only one spin mark if it wasnt... ?

Something else I just read is you can jack up the rear of the truck and spin one tire. If the other spins the same direction, its limited slip.

Im just a little nervous about possibly messing something up. I guess the easy thing would be to just add the friction modifier and forget about it. But would still just like to know what the heck Ive got

You've got an e-locking diff, that means its open til you hit the axle lock button so you can use diff/gear oil without the additive but if you go with a synthetic, it will have the additive anyway. You're fine with any gear oil provided its the right weight. Thats 100%

 

[kapinallinen2]

If the other spins the same direction, its limited slip.

That is old school limited slip.
Ram limited slip only engages with enough differential side loading that puts pressure on the clutch plates, during a fairly hard acceleration.
You have an e-locker if you have the axle lock button, 100% no doubt.

 

[Rebob0510]

I have basically the same truck, 2020 with 3.92 and electronic locker. I went with Valvoline Full Synthetic 75-140 in the plastic pouch, It made it very easy to refill. I went with (3) quarts to ensure I had enough. I did NOT add the LSD additive to mine. On a side note when I dumped the oil at 80K it looked pretty much new still. I bought the truck with 30k so unless the first owner changed it, it was still the OEM oil

 

[jc312]

I have basically the same truck, 2020 with 3.92 and electronic locker. I went with Valvoline Full Synthetic 75-140 in the plastic pouch, It made it very easy to refill. I went with (3) quarts to ensure I had enough. I did NOT add the LSD additive to mine. On a side note when I dumped the oil at 80K it looked pretty much new still. I bought the truck with 30k so unless the first owner changed it, it was still the OEM oil

That's good to know! Mines only got 55k, but got about 10k towing a camper.

I changed my other truck df today, a 93 toyota pickup with 120k, and it didn't look bad really. Good chance its the original fluid, but can't be sure. Bought it with 88k

 

[jc312]

Really appreciate all the help, thanks alot!

My next plan is to change the transmission fluid & filter. Looks like a bit of work from what Ive seen. One question that would help me decide if I want to try it myself. Can it be done without lifting the truck? Ive watched videos where the truck was put in 2nd gear while lifted as part of the process, but have heard it can be done on the ground as well...

 

[kapinallinen2]

Really appreciate all the help, thanks alot!

My next plan is to change the transmission fluid & filter. Looks like a bit of work from what Ive seen. One question that would help me decide if I want to try it myself. Can it be done without lifting the truck? Ive watched videos where the truck was put in 2nd gear while lifted as part of the process, but have heard it can be done on the ground as well...

Needs to be on jack stands in order to drop the y-pipe, at least this is what I did.
edit: might raise the transmission next time.

 

[Rebob0510]

Really appreciate all the help, thanks alot!

My next plan is to change the transmission fluid & filter. Looks like a bit of work from what Ive seen. One question that would help me decide if I want to try it myself. Can it be done without lifting the truck? Ive watched videos where the truck was put in 2nd gear while lifted as part of the process, but have heard it can be done on the ground as well...

I can chime in on this also LOL. I changed the pan/fluid on my truck around the same time I did the rear end oil. I changed mine with the front tires on ramps and jack stands under the rear end so the tires could rotate when you do the fill procedure. I dont think it would be very fun to do on the ground with the limited space, It wasn't fun on the ramps but also wasn't horrible. I went with a PPE aftermarket pan that holds a few more quarts then the stock pan and also has a replaceable filter unlike the stock pan. If I still own the truck and change the fluid again next time will be filter/oil and not the whole pan like the OEM one forces you to do. I removed the bolts like in the video and raised the transmission to gain the clearance to remove the pan, Here in NY I didnt dare try to take my exhaust apart like Kapinallinen2 did LOL

Its honestly not that bad of a job. I used this video as my guide....

 

[jc312]

Needs to be on jack stands in order to drop the y-pipe, at least this is what I did.
edit: might raise the transmission next time.
View attachment 210770View attachment 210771

I can chime in on this also LOL. I changed the pan/fluid on my truck around the same time I did the rear end oil. I changed mine with the front tires on ramps and jack stands under the rear end so the tires could rotate when you do the fill procedure. I dont think it would be very fun to do on the ground with the limited space, It wasn't fun on the ramps but also wasn't horrible. I went with a PPE aftermarket pan that holds a few more quarts then the stock pan and also has a replaceable filter unlike the stock pan. If I still own the truck and change the fluid again next time will be filter/oil and not the whole pan like the OEM one forces you to do. I removed the bolts like in the video and raised the transmission to gain the clearance to remove the pan, Here in NY I didnt dare try to take my exhaust apart like Kapinallinen2 did LOL

Its honestly not that bad of a job. I used this video as my guide....

Appreciate the help! Ive watched a video or 2, but need to watch again. I was thinking Jack stands could work. Putting the front tires on ramps is a good idea, something I hadn't thought of

Mines a off-road model with slightly higher ground clearance, still not the greatest place to work under. Will do what yall were saying and get it up higher

Im in the south, so no salt corrosion to have to deal with

Im gonna check on the bigger aftermarket pan, ive heard of it.

Thanks again

 

[Rebob0510]

One thing to do with the ramps is once you drive up on them take a ratchet strap around the tread of each tire and secure them to the ramps. With the wheels off the ground nothing will keep the truck from being able to roll, With the straps it will be like having a wheel chalk and keep the truck from moving while you are under it. You are lucky to be in the south, I'm sure if you went the exhaust way your will come apart nice and easy. If you choose to leave it and raise the pan that way is pretty easy also, Especially with it on the ramps and jack stands. You don't have to raise it far, about 1". With your truck being a 2020 like mine go with the PPE pan if you do go aftermarket. I learned the hard way that some 2020's (mine is one of them) have shorter catalytic converters which puts the exhaust crossover too close to the pan causing it not to fit. I originally went with a B&M pan (+4 quarts from stock) and got my pan off only to realize it wouldn't work, Had to put the stock pan back on with new oil because I had the truck all apart at work. Didi a bunch of homework and then went with the PPE pan (+2 quarts from stock) and it worked perfectly

This is the thread I made on my transmission pan issues...

R

Thread 'B&M 70395 8HP75 transmission pan DID NOT FIT my 2020 ram 5.7'

Feb 3, 2025

Today I attempted to install a B&M Hi-Tek Transmission pan on my 2020 5.7 5th Gen and it did not fit. Project was going well, thankfully for youtube I had watched a bunch of videos so I knew what I was getting into. Got the old pan off easily, Cleaned the gasket mating surface, Installed the filter and filter extension, then slid new pan up and the sump for the extra 4 quart capacity hit on the exhaust crossover tube. When I first held it up it wasn't even close to bolting up... I marked where it was close and got the BFH out and flattened the exhaust pipe some. After doing that I could...

• Rebob0510
• Replies: 35
• Forum: 5th Gen General Discussion

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