Gear oil choices for 3.92 LSD

[keanezheng]

Thanks guys for your input, let me reciprocate with a good deal. Amazon has the best price for the Mopar friction modifier. $7.15 per bottle. Seems legit with 1400+ reviews. Cheaper than Summit or eBay or any dealership for sure.

 

[1BADRAMLIMITED]

Thanks guys for your input, let me reciprocate with a good deal. Amazon has the best price for the Mopar friction modifier. $7.15 per bottle. Seems legit with 1400+ reviews. Cheaper than Summit or eBay or any dealership for sure.

thats where i got mine

 

[kdoublep]

That's where I got mine

 

[mtjag]

So, thinking about using the MOPAR 75w140 with MOPAR friction modifier in the rear axle since I have LS and the Valvoline 75w90 in the front axle. It would be my first change at 57000 miles and looking at the space for the front axle, getting a bottle positioned in there seems a bit dicy where as the Valvoline package is much more flexible. Any comments or suggestions?

 

[mtjag]

So, thinking about using the MOPAR 75w140 with MOPAR friction modifier in the rear axle since I have LS and the Valvoline 75w90 in the front axle. It would be my first change at 57000 miles and looking at the space for the front axle, getting a bottle positioned in there seems a bit dicy where as the Valvoline package is much more flexible. Any comments or suggestions?

by the way, we tow a 5800# travel trailer quite a bit, likely 50% of the time, and I have the 3.92 rear axle

 

[mtjag]

What's the downside if there is not enough MOPAR friction additive in the rear diff with limited slip. In other words, if I didn't get a full 5oz of the friction additive in the rear fluid, what will happen?

 

[TheWaterman83]

What's the downside if there is not enough MOPAR friction additive in the rear diff with limited slip. In other words, if I didn't get a full 5oz of the friction additive in the rear fluid, what will happen?

If you under-add or don't add any of the slip additive in a truck with an limited-slip rear, you'll get chatter going around turns and wheel chirping.

Trucks w/o limited slip rears (Rebel with e-locker) = Limited slip additive or not, doesn't matter.
Trucks w/ limited slip rears (non e-locker) = You must add limited slip additive, even if the gear oil has it in it already.

I used Amsoil Severe Gear oil in my front and rear diff, with no added limited slip additive as I have the e-locker.

 

[mtjag]

If you under-add or don't add any of the slip additive in a truck with an limited-slip rear, you'll get chatter going around turns and wheel chirping.

Trucks w/o limited slip rears (Rebel with e-locker) = Limited slip additive or not, doesn't matter.
Trucks w/ limited slip rears (non e-locker) = You must add limited slip additive, even if the gear oil has it in it already.

I used Amsoil Severe Gear oil in my front and rear diff, with no added limited slip additive as I have the e-locker.

Thanks for that. I used the MOPAR and added the MOPAR limited slip additive, I just don't know if I got enough in there. I measured out 5 oz but had to put it in one of the larger MOPAR bottles and then pumped it in. After I topped off, I noticed there was still maybe a couple of oz of mixed 75w140 and MOPAR additive in the first bottle I used. So, just second guessing now if I got enough in there. My dilemma is to drain out some and put more additive in, but that would also drain out some of the initial additive. I put in. I guess if it starts to chatter or chirp, I'll just do it all again.

 

[1BADRAMLIMITED]

If you under-add or don't add any of the slip additive in a truck with an limited-slip rear, you'll get chatter going around turns and wheel chirping.

Trucks w/o limited slip rears (Rebel with e-locker) = Limited slip additive or not, doesn't matter.
Trucks w/ limited slip rears (non e-locker) = You must add limited slip additive, even if the gear oil has it in it already.

I used Amsoil Severe Gear oil in my front and rear diff, with no added limited slip additive as I have the e-locker.

So I have a question.

I have a truck with axle lock button and down hill assist as well as 4hi lo and auto 4wd.

With that said if I activate the axle lock and then turn (left or right I get a chirping sound almost as if the side I’m turning to is pulling and not rolling. Is this normal?

I don’t get any error messages but I found it very odd and honestly scared me when I 1st used it

 

[kdoublep]

I'm pretty sure it's normal because your tires are spinning at different rates and theyre locked. I get something similar in 4 lo when turning. It's just not something I'm used to.

I use 4 auto often. 4 hi rarely, and never used 4 lo in practice.

I could be wrong on the noise.

 

[1BADRAMLIMITED]

I'm pretty sure it's normal because your tires are spinning at different rates and theyre locked. I get something similar in 4 lo when turning. It's just not something I'm used.

I use 4 auto often. 4 hi rarely, and never used 4 lo in practice.

I could be wrong on the noise.

That’s my thought. I once had a looooong time ago a 240sx and welded the diff in it and it did something similar just a lot more violent but I’m guessing same concept.

 

[CHeYeNNe71]

So I have a question.

I have a truck with axle lock button and down hill assist as well as 4hi lo and auto 4wd.

With that said if I activate the axle lock and then turn (left or right I get a chirping sound almost as if the side I’m turning to is pulling and not rolling. Is this normal?

I don’t get any error messages but I found it very odd and honestly scared me when I 1st used it

Only lock when on a slippery surface ie dirt, gravel, snow, etc. Dry pavement can cause damage.

 

[TheWaterman83]

So I have a question.

I have a truck with axle lock button and down hill assist as well as 4hi lo and auto 4wd.

With that said if I activate the axle lock and then turn (left or right I get a chirping sound almost as if the side I’m turning to is pulling and not rolling. Is this normal?

I don’t get any error messages but I found it very odd and honestly scared me when I 1st used it

100% normal. What was said about the e-locker on drive pavement is false. As long as you go in a straight line on dry/firm ground with the e-locker, it's not an issue. What you are experiencing is normal. The axle is locked and the inner or outer wheel, around turns, can't keep up/grip the same as the other wheel.

Now if you are making turns with the e-locker, yes, you should make sure you're not on firm/dry pavement. Same with 4x4. Although, you don't have control of the 4wd because it's auto.

I typically use my e-locker at boat ramps along with the 4x4 because I'm going straight, and I can't afford to slip. Many of the ramps I use to hunt are sand, dirt, or mud.

 

[SD Rebel]

100% normal. What was said about the e-locker on drive pavement is false. As long as you go in a straight line on dry/firm ground with the e-locker, it's not an issue. What you are experiencing is normal. The axle is locked and the inner or outer wheel, around turns, can't keep up/grip the same as the other wheel.

Now if you are making turns with the e-locker, yes, you should make sure you're not on firm/dry pavement. Same with 4x4. Although, you don't have control of the 4wd because it's auto.

I typically use my e-locker at boat ramps along with the 4x4 because I'm going straight, and I can't afford to slip. Many of the ramps I use to hunt are sand, dirt, or mud.

I stupidily forgot to turn off my E-Locker today after pulling a boat up from a ramp. I had my buddies 5,000 lbs boat/trailer when I made two hard turns, I noticed the rear tire chirping both times before I realized I left the locker on.

I guess it's a good sign the tires lost traction instead of hearing crunching gears, but hoping for no damage. The drive after felt normal, no weird sounds or feelings after, but time will tell.

 

[2021QCBH]

I’m running 75-90 Amsoil severe gear in both diffs since 50k. (3.21 gears and almost 90k now).

My rear started making a very faint noise on very light deceleration around 62 mph around 50k before I changed fluid.

Now it’s a bit louder and has expended its range from about 60-65 pending how hot the fluid is. Hoping I can make it to 150k then rebuild it with a LSD (the thing I miss the most on this truck).

Might change it out again and move to the 75-140 to quiet it down and annoy me less.