Gear Oil for 5.13 Gears?

ERAUGrad04 · Mar 4, 2015

Getting regeared next week to 5.13s in my Rubi axles. Running 37" tires and will do a lot of highway driving on the hilly highways in CA.

Should I be running 75w90 or 85w140. Drew at ORE says the heavier weight is what they run and I'm in agreement based on my driving. However, just curious what the group thinks.

Thanks!

2013rubirick · Mar 4, 2015

I run 85w140. That is what Eddie recommended to me.

07JKSahara · Mar 4, 2015

Curious, would it be different for other gear ratios? Locker vs open?

ERAUGrad04 · Mar 4, 2015

2013rubirick said:
I run 85w140. That is what Eddie recommended to me.

Good to hear. I can see the benefits of the thicker oil when it comes to the high speed and heat generated by the faster gear speeds.

Curious, synthetic?

2013rubirick · Mar 4, 2015

ERAUGrad04 said:
Good to hear. I can see the benefits of the thicker oil when it comes to the high speed and heat generated by the faster gear speeds.

Curious, synthetic?

Well I heard that a synthetic oil can hurt the arb locker seals so I run non synthetic valvoline 85w140.

ERAUGrad04 · Mar 4, 2015

2013rubirick said:
Well I heard that a synthetic oil can hurt the arb lock seals so I run non synthetic valvoline 85w140.

I'm running factory Rubi lockers front and rear, but this will be good to remember for future upgrades. Thanks!

2013rubirick · Mar 4, 2015

07JKSahara said:
Curious, would it be different for other gear ratios? Locker vs open?

For gears like 4.10's I don't think you need such a thick fluid. It's not generating as much heat as lower gears such as 5.13's and 5.38's. You would be fine with a 75w90 oil.

t8er · Mar 4, 2015

I run 75/90 up front and 85/140 in the rear. That's what jeep uses if you have the tow package because of higher heat etc so 85/140

07JKSahara · Mar 4, 2015

2013rubirick said:
For gears like 4.10's I don't think you need such a thick fluid. It's not generating as much heat as lower gears such as 5.13's and 5.38's. You would be fine with a 75w90 oil.

Much obliged.

toxicwaste29 · Mar 4, 2015

I run royal purple in mine. Its 90w I believe. I don't have lockers. Its the same stuff I run in my muscle car. I did send an email to royal purple once about water in the oil and they said just let it sit on a bucket for some time. The water and mud sinks to the bottom of the bucket then just drain out the good gear oil and reuse it. Of course I'm sure the same applies to any oil.

Mjay · Mar 5, 2015

toxicwaste29 said:
I run royal purple in mine. Its 90w I believe. I don't have lockers. Its the same stuff I run in my muscle car. I did send an email to royal purple once about water in the oil and they said just let it sit on a bucket for some time. The water and mud sinks to the bottom of the bucket then just drain out the good gear oil and reuse it. Of course I'm sure the same applies to any oil.

Or you could just change all of it. Don't know about everyone else here, but if it's obviously contaminated with water and muddy crap I don't want any of that crap in my gears or expensive locker.

toxicwaste29 · Mar 5, 2015

Ya that's the other side of the story. I always just replace mine with fresh stuff. Just passing along what was told to me.

Tigrcky · Mar 5, 2015

Be sure to add a friction modifier if you have a locker or limited slip

ERAUGrad04 · Mar 5, 2015

Tigrcky said:
Be sure to add a friction modifier if you have a locker or limited slip

I thought friction modifier was only necessary with a limited slip and not with a locker? Do I have that wrong?

Tigrcky · Mar 5, 2015

ERAUGrad04 said:
I thought friction modifier was only necessary with a limited slip and not with a locker? Do I have that wrong?

All the tech notes for oem lockers have mentioned a modifer, some oils already have them ie if labeled for limited slip diffs or lockers

Tanner505 · Mar 5, 2015

ERAUGrad04 said:
I thought friction modifier was only necessary with a limited slip and not with a locker? Do I have that wrong?

They DO NOT need the modifier if you have lockers if you have limited slips you do need it, all synthetics have friction modifier in them

ERAUGrad04 · Mar 5, 2015

Tigrcky said:
All the tech notes for oem lockers have mentioned a modifer, some oils already have them ie if labeled for limited slip diffs or lockers

What tech notes? If the oil has it in it that's one thing, but I really don't think it needs to be added. The lockers do not have any sort of friction type clutches in them; only a mechanical locking ring.

Tigrcky · Mar 5, 2015

ERAUGrad04 said:
What tech notes? If the oil has it in it that's one thing, but I really don't think it needs to be added. The lockers do not have any sort of friction type clutches in them; only a mechanical locking ring.

Look automatic lockers do, I'm actually an ase certified mechanic. Don't like to say it much cause then people really pour the hate on, selectable lockers don't need it but automatic ones do and limited slips but like I said most oils already have it added

ERAUGrad04 · Mar 5, 2015

Tigrcky said:
Look automatic lockers do, I'm actually an ase certified mechanic. Don't like to say it much cause then people really pour the hate on, selectable lockers don't need it but automatic ones do and limited slips but like I said most oils already have it added

Not trying to hate, I promise! Just trying to understand what is necessary. The lockers in the Rubicon are not automatic. I think it's a moot point since I'll probably be running synthetic anyways, but a good discussion nonetheless.

:beer::beer:

Tigrcky · Mar 5, 2015

ERAUGrad04 said:
Not trying to hate, I promise! Just trying to understand what is necessary. The lockers in the Rubicon are not automatic. I think it's a moot point since I'll probably be running synthetic anyways, but a good discussion nonetheless.

:beer::beer:

Awesome and I'd go 85w140

Gear Oil for 5.13 Gears?

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