Gear Oil Recommendations?

Hello Guys,

Just recently inherited a 1996 Cherokee 4.0 from my boss. The vehicle is equipped with a Dana 30 and the Chrysler 8.25" rear end, non abs equipped. As I am missing the owners manual, I was wondering what gear oil was recommended for use in the differentials and the transmission? Does Mobil 1 make a suitable product? Thank you all for any information and advice.

Regards,

Cody

i just run what ever cheap dyno oil in what ever weight my FSM tells me to and exercise regular maintenance. i dont have the FSM on hand, so i cant tell you what it says to use. sorry. but ive found that even the big box part stores usually recommend the same thing the FSM does.

maybe im cheap... but im also relatively uninvested into my axles. zero problems.

For massive overkill, you can't go wrong with Redline. Probably more important is to get yourself a pair of LubeLocker gaskets so you'll actually change the gear oil every 50K (or after you dunk it) like you're supposed to but nobody ever does.

I believe the spec calls for a 75W90 or 80W90 (not xW140 which is the other likely option.) I'm running Redline Heavy Shockproof which is about a 90 weight but supposedly protects better against abuse. You could also run their regular 75W90 gear oil and maybe pick up a little gas mileage. Don't forget to change the oil in the transfer case as well (mine was black at 80K miles) I used Redline D4 ATF in the transfer case and also in my AW4 automatic transmission.

I'm a big believer in changing ALL fluids regularly; oil at regular intervals and then axles, transfer case, and transmission every 50K miles; power steering fluid maybe at the same time, then brake fluid every 2 years and coolant every 4 (if you haven't had to drain it for repairs.) Your vehicle will thank you.

Side note: there's a Chrysler spec for power steering fluid. Don't know how important it is to adhere to it, but based on my experiences with European stuff I actually bought a bottle from the dealership (thinking of what happens if you put regular ATF or red PS fluid in a car that takes Pentosin... bad things man)

Thank you guys for the recommendations. It is greatly appreciated. As I don't know the history of the car I have spent the past week flushing the coolant, changing the brake fluid, and changing the oil and belt. I did not even think to change the Power Steering fluid, so that will probably be next on the project list as well. How much oil should I purchase to change the fluid in both differentials and the transmission?

Don't remember and can't look because I am on my phone, but probably 3-4 quarts gear oil for both axles and I think 6-8 quarts ATF for trans and transfer case. Will verify later if nobody's responded. Good on you for changing the brake fluid, nobody does it, but they replace calipers and I don't . Don't forget to grease all the steering bits and the slip piece in the front driveshaft (and any U-joints that may have been replaced with greasable ones over the years.)

Just did my trans service, t-case fluid change, and front axle fluid change. Info's still fresh.

I used Valvoline Dex/Merc in both the trans and t-case. Just make sure the fluid is compatible with Dexron III, its needed. I changed out the filter too, and suggest it.

With the front axle, i went Mobil 1 75w90 synthetic. A very knowledgeable buddy also told me to run 75w140 in the rear for when i change that.

+1 on the Redline gear oil recommendation.

I used 75w90 in both differentials. I know it sounds strange, but this fluid (even being a synthetic) slowed down my front pinion seal leak almost completely. It is barely even wet around the seal now. I normally don't buy one brand over another, but I will continue to buy the Redline.

I'd use 75w90 in both axles under normal use, and 75w90 front and 75w140 rear if you tow frequently.

How much oil should I plan on buying?

OK, straight outta my '99 owner's manual

Fluid types:

Automatic Transmission, 4.0 Engine - Dexron III or Mercon (I believe MoPar has officially superseded this to ATF +4, but this is in fact an Aisin-Warner transmission so I don't understand that - I'd stick with Dex/Merc)

Axle Diff, Front and Rear - SAE 85W90, API-GL5. For trailer towing applications use SAE 75W140 Synthetic Gear Lubricant in rear axle. Models equipped with Track-Lok require an additive.

Power Steering Pump - MoPar Power Steering Fluid (that's all that it says, this is why I got mine from the dealer, no spec is given.)

Transfer Case - Dexron III or Mercon

Capacities:

Engine Oil - 6 qts

Transmission, drain and fill - approximately 4 quarts (SIC - buy at least five I guess) Level is checked hot and in Park, after shifting through all ranges first. If checking cold, only fill to the "ADD" mark using this procedure.

Transfer Case - Selec-Trac (NP242, with "Full Time" 4WD position) 2.85 pints

Transfer Case - Command-Trac (NP231, common 2H/4H/N/4L quadrant) 2.2 pints

Front Axle - 3.0 pints

Rear Axle - Dana - 3.4 pints

Rear Axle - Chrysler - 4.4 pints

good luck!

Be careful with that stupid rubber fill plug that Chrysler
put in the 8.25 rear diff. They're easy to split with age, and
most seep oil after a while.

That rubber plug made me install a stainless steel cover
with a 'real' metal plug. I did a 'fill and forget' with
Mobil 1 75W140 synthetic.

I paid about $80 for the cover from Summit IIRC...

yeah, mine seeped after a refill (the turdy-five has the same stupid design cover...) Carquest has a replacement rubber plug for cheap though.

I thought about taking a pipe tap and tapping the cover for a plug, as I have a set of large pipe taps inherited from my grandfather (who was a tubefitter, although he apparently didn't think I'd want his nice rolling benders or flaring tools and sold them before he passed away... WTF?) but measuring eyeballically, it looks like the hole in the 35 cover is slightly larger than it would be if it were to be tapped with a 1/2" pipe tap so the plug might sit too deep and/or not seal. Has anyone tried this, and/or have a spare cover they'd be willing to sacrifice for the grand experiment?

I use Valvoline 75w90 in mine. It's what the local parts stores stock and is waaay cheaper than any of the high end stuff they have. For stock open axles I decided to go with the cheaper of the fluids. I don't mind spending money for redline fluid in other applications but for my jeeps differentials, Valvoline is just fine. It smells horrible and gets on everything but I change it on schedule and never had an issue.

Thank you all for your help and advice. It is greatly appreciated. I will be sure to secure a new plug before I pop the differentials open.

If you're in a hurry the axles do not have drain plugs... but you can still change "most" of the fluid with a suction gun. Mine is a Lincoln and is the only one I've had that's worth a shit. It's also handy for filling the diffs - unscrew the top, fill with gear oil, and use it to push the gear oil in. If you do take the covers off (the right way to do it) I'm more than happy with my LubeLockers; the outsides are bone dry. But if you're on a real tight budget RTV will work just as well.

Any brand of the proper weight in the axles. Redline MT (75-90) in the AX15 is an improvement is shifting,especially when cold, my wife even noticed the difference

I have only one thing to add, I'm not sure how you use your XJ but if you wheel in water regularly, don't bother getting anything fancy. Just whatever's cheapest.

I went with Amsoil the first time around thinking I was doing myself a favor in the long run. 15K miles later and I've been in to both differentials at least twice for various reasons (water, axle seals, leaking after peeling the rear cover back) and that fancy gear oil is all gone. I just run whatever's cheapest now.

Hi Guys, currently it is used mostly around town with some weekend off roading and camping. Not too much water exposure currently.

Spend the money for redline mt-90 or redline mtr
Save the money on diff oil. Frequency is more important than high dollar oil here.

Order a set of lube lockers, scrape rtv, smile knowing you will not have to do it again.

souske said:

Spend the money for redline mt-90 or redline mtr
Save the money on diff oil. Frequency is more important than high dollar oil here.

Order a set of lube lockers, scrape rtv, smile knowing you will not have to do it again.

Click to expand...

I use some gasket remover I got at napa, it dissolves the RTV pretty easily. It just sprays on, wait a little bit and then just wipes off. I have a nice gasket scrapper for the hard to get at stuff but it's not much hassle at all.

iwannadie said:

I use some gasket remover I got at napa, it dissolves the RTV pretty easily. It just sprays on, wait a little bit and then just wipes off. I have a nice gasket scrapper for the hard to get at stuff but it's not much hassle at all.

Click to expand...

Again it depends on how often you are opening your diffs up... but I wish I'd have spent the 20 bucks per axle up front on lube lockers. Easily would have paid for themselves by now in time saved alone. If you're servicing at the factory interval, don't worry about them. Any more frequent, and just buy them now. Seriously.

Also, They stay sealed much better than RTV. I keep peeling back the cover on my 8.25 and had to reseal it when I had RTV on it. Swapped for a lubelocker and the next time out, peeled it back in the exact same place. But no leak this time. That alone made it worth the money.