Front and Rear Diff Fluid

[JeepMan82]

Hello everyone, I am new here and a new KJ owner. I have a 2007 Liberty that is coming up on it's 60,000 mile service and I want to get things in order now as I will hit that millage mark in a hurry with all the driving I do. I am confused as to which oil to use. Should I run the 75W90 rear and the 80W90 front or can I get away with running the 75W90 front and rear? I don't do much off road driving and I probably will never tow a trailer with it. I do however live in central Arkansas and do all mainly highway driving with it. At times with all the rain we sometimes get I do at times run through flooded roads and I know that after any water crossing change the diff fluids.

Thanks in advance for the help in this.

 

[TwoBobsKJ]

Welcome!

If you don't do any offroading then go with the 75W-90 in both the front and rear.

However, a cheaper alternative - and a good one since you live in the heat of the South - is 85W-140 dino oil. Very inexpensive and actually does a better job of sticking to the gear sets than synthetic. Recommended by diff and gear shops. You'll need approximately 2 quarts per axle.

Don't forget about your transfer case! Two quarts of ATF+4 only - don't use standard ATF.

Have fun!

Bob

 

[JeepMan82]

Welcome!

If you don't do any offroading then go with the 75W-90 in both the front and rear.

However, a cheaper alternative - and a good one since you live in the heat of the South - is 85W-140 dino oil. Very inexpensive and actually does a better job of sticking to the gear sets than synthetic. Recommended by diff and gear shops. You'll need approximately 2 quarts per axle.

Don't forget about your transfer case! Two quarts of ATF+4 only - don't use standard ATF.

Have fun!

Bob

Thanks for the info. I do plan to do some off roading with my KJ but nothing severe like rock crawling. Thanks for reminding of the Transfer Case I comepletely forgot about it. I have the trac lock option in the rear diff, will I need the Limited Slip additive I keep hearing about?

 

[tjkj2002]

Thanks for the info. I do plan to do some off roading with my KJ but nothing severe like rock crawling. Thanks for reminding of the Transfer Case I comepletely forgot about it. I have the trac lock option in the rear diff, will I need the Limited Slip additive I keep hearing about?

Yes you will need the friction modifier for the rear diff,add 1st before adding gear oil.


Just a side note you can use any ATF for the t-case,it's a closed system and they only recommend ATF+4 since the trans uses the same as does the powersteering.You can run 5w-30/5w-20 motor oil if you so please in the t-case since ATF is about the same as 5w-30/5w-20.

 

[TheBlueKJ]

Thought there was something in there that made it so you could only use the ATF +4, like a pump or something

 

[tjkj2002]

Thought there was something in there that made it so you could only use the ATF +4, like a pump or something

Nope as no t-case offered in a KJ is clutch based or electronic that requires any special fluid.Just don't use any fluid thicker then 5w-30 as the t-case does have a internal cooler.

 

[JeepMan82]

Thanks everyone I really appreciate all the info. Thanks for helping a begining Jeep owner.

 

[1BADKJ]

There is an internal oil pump in a 231 T-case

 

[JeepMan82]

How can I tell what Transfer Case I have?

 

[JeepMan82]

Welcome!

If you don't do any offroading then go with the 75W-90 in both the front and rear.

However, a cheaper alternative - and a good one since you live in the heat of the South - is 85W-140 dino oil. Very inexpensive and actually does a better job of sticking to the gear sets than synthetic. Recommended by diff and gear shops. You'll need approximately 2 quarts per axle.

Don't forget about your transfer case! Two quarts of ATF+4 only - don't use standard ATF.

Have fun!

Bob

Being in the South and the cold winters we can get here would the 85W140 hurt the gears in the diffs or would it help?

 

[tjkj2002]

Being in the South and the cold winters we can get here would the 85W140 hurt the gears in the diffs or would it help?

I use 85w-140 in both diffs year round and I live in Colorado.

 

[1BADKJ]

I use 85w-140 in both diffs year round and I live in Colorado.

Not everyone is lucky enough to live in one of the rock crawling capitols of the USA. :hail: Lucky bastard.

 

[Dave]

I use 85w-140 in both diffs year round and I live in Colorado.

Yeah, and you haven't had OEM diff's "since hector was a pup".....LOL

But anyway, I am running 85-140 in OEM diff's.....no problems.

Dave

 

[TwoBobsKJ]

Being in the South and the cold winters we can get here would the 85W140 hurt the gears in the diffs or would it help?

It's just that the dino oil is a bit thicker than the synth and so when things get hot the oil will retain its viscocity. I run that oil here in Northern Ohio and on the really cold mornings I can tell its "gummy" but it loosens up in a couple miles. You'll be fine.

Bob

 

[TwoBobsKJ]

How can I tell what Transfer Case I have?

You can tell by how many positions you have on your T-Case shift handle:

- The CommanTrac has 2WD, Part Time 4WD, Neutral and 4LO
- The Select Trac has 2WD, Part Time 4WD, Full Time 4WD, Neutral and 4LO.

Bob

 

[WickedBruce]

I also am using the 85w140 with no issues

 

[TheBlueKJ]

You can tell by how many positions you have on your T-Case shift handle:

- The CommanTrac has 2WD, Part Time 4WD, Neutral and 4LO NP231
- The Select Trac has 2WD, Part Time 4WD, Full Time 4WD, Neutral and 4LO.NP242

Bob

Labeled them for ya, and if you take the time to actually look at the tcase it will have a badge saying which tcase it is whether it be NP231 or NP242

 

[tjkj2002]

Yeah, and you haven't had OEM diff's "since hector was a pup".....LOL

But anyway, I am running 85-140 in OEM diff's.....no problems.

Dave

Ran 85w-140 in the stock diffs also:boxing:

 

[JeepMan82]

Thanks for all the info everyone, you've all been a great help.

 

[92fox]

How often should the T-case and diff fluids be changed if running the 5w-30 and 85w-140?