99' Jeep 6 CYL/ Auto - Fluid Change

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JeepGirlTX87

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Dec 9, 2011
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Location
College Station, TX
Hey there,

I need fluid recommendations for the maintenance I plan to do below:

1. Drain/Refill Automatic Transmission Fluid/Filter
2. Drain/Refill Front & Rear Axle - Differentials
3. Drain/Refill Transfer Case Fluid

On #1, I'm currently using PureOne and Wix for filters, is there a better advisable brand for the transmission filter?
 
I have never heard of a bad wix trans filter. and i do run alot of wix stuff and really like the price and quality. We dont have pureone filters up here but i hear alot from the guys down south. (good things) sometimes oem filters are better than replacement but sometimes its the other way around.
 
For your automatic transmission, I believe it's spec'd for ATF+4. I've used the "house" brand filter (AAP usually) with no issues, and WIX is generally a good filter. There's a magnet in the pan that catches the iron particles.

Axles - I'd go with whatever good quality synthetic differential lube is available. Right now I've got some Amsoil 80w90, but I have open differentials. If you have limited slip it takes 70w140.

Transfer case - I've been using Amsoil ATF for the last few changes with good results in both our Jeeps. It's spec'd for ATF+4 also, but the TC is not sensitive to other fluids like the transmission is.
 
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Originally Posted By: Kuato

Transfer case - I've been using Amsoil ATF for the last few changes with good results in both our Jeeps. It's spec'd for ATF+4 also, but the TC is not sensitive to other fluids like the transmission is.


To add to this, looks like Amsoil has developed and is now recommending a tractor gear lube for Jeep TCs. I may have to check it out. But check your owner's manual, I think yours is ATF+4 also.

How did you manage only 51k on a '99? Wow....that's less than 3 years of driving for me.
 
Amsoil ATF for the transmission and TC. Amsoil severe gear for the diff. But check out their website for exact specs. I have SelecTrac and you may need something different of you have QuadTrac.
 
if you don't want to go amsoil...

Mobil 1 in the axles has been great in both jeeps I've owned.
Castrol ATF+4 has been very nice in my WK (I'd use amsoil but i have the lifetime drivetrain warranty, so needs to me +4).

Mobil 1 universal ATF has been great in previous transfer cases... though you'll probably be better just using whatever ATF you use in the transmission.

Avoid the cheapo transmission filters... sometimes the moldings aren't quite right and can make installation a pain, even if the filter media looks exactly like oem.

my 08 grand currently runs amsoil in the diff-- 110 weight. it's spec'd for 140 but has been just fine on 110. yours may actually want 90 weight. unless you are flogging it, either amsoil or mobil will be fine. I highly suggest synthetics in the driveline as I have seen small mpg increases every time i've gone away from dino in axles and transmissions.

M
 
On the transmission situation:

I called all 3 parts stores, no one had any wix trans filter in stock.

I called dealer to ask what they had in stock, etc. The same dude who recommended wix for the air filter.

He said when they'd order aftermarket transmission filters, they had issues fitting in a lot of cases.

So I bought an OEM transmission filter and gasket.

And we started talking about the different transmission fluids, etc.

He freaked me out about, about some dude who used aftermarket transmission fluid on a fleet, and ruined 11 transmissions, so I got stuck buying the OEM transmission fluid as well, the ATF+4.

I wanted to change the case & differentials, but a lot of people are telling me to just hold off on it, that it's not a big deal to change, to leave it for right now esp. if it's clean.

So we'll check it when we do the other fluid changes this week to at least ensure it's not dirty.

I'll update then.

If you guys feel they should be changed, let me know why.

P.S. On the Jeep, I just bought it, I was looking for 6 months for one in this condition, lol. I don't drive a lot, so I don't see it reaching 100K any time soon.
 
Last edited:
Originally Posted By: JeepGirlTX87
On the transmission situation:

I called all 3 parts stores, no one had any wix trans filter in stock.

I called dealer to ask what they had in stock, etc. The same dude who recommended wix for the air filter.

He said when they'd order aftermarket transmission filters, they had issues fitting in a lot of cases.

So I bought an OEM transmission filter and gasket.

And we started talking about the different transmission fluids, etc.

He freaked me out about, about some dude who used aftermarket transmission fluid on a fleet, and ruined 11 transmissions, so I got stuck buying the OEM transmission fluid as well, the ATF+4.

I wanted to change the case & differentials, but a lot of people are telling me to just hold off on it, that it's not a big deal to change, to leave it for right now esp. if it's clean.

So we'll check it when we do the other fluid changes this week to at least ensure it's not dirty.

I'll update then.

If you guys feel they should be changed, let me know why.

P.S. On the Jeep, I just bought it, I was looking for 6 months for one in this condition, lol. I don't drive a lot, so I don't see it reaching 100K any time soon.


The OEM trans filter was the one to get if you could not get a WIX easily.

I am not sure I would classify Amsoil multi-vehicle ATF as some "aftermarket trans fluid". "Aftermartet trans fluid" could be almost anything, from something that was not spec'ed for the AT+4 to a Dollar store ATF to generic ATF where they add an additive to magically make it ATF+4 (or not). Amsoil will be better than OEM ATF+4 for your Jeep. Amsoil ATF is expensive and a bit of a pain to get, but its the best ATF out there.
 
Use atf+4 in transmission and transfercase.
frankly you wont find many oils thats better than atf+4...
 
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DO change the differential/axle oils. what's in there is old. how much did the dealer charge for the ATF+4? If it's over 9-10/qt you might take it back and get something a little cheaper elsewhere, though you'll only be saving a few dollars.

The transfer case has a big heavy chain in it. the chain is only under load when in 4x4, which for most jeeps isn't often. However, chains are generally hard on oil, and there's not a lot of oil in there.... DO change that.

Good luck. You're doing the right stuff!
 
What transfer case do you have?

I would change the fluid in it and the diffs.

Also dont forget the cooling system, power steeing and brake fluid.

Jeepforum.com, Jeepsunlimited.com are some good sites to look at.
 
Hey there,

To answer the questions:

1. I paid $9.20 total (w/tax) per quart for Mopar ATF+4. Most likely we're just draining the pan, and refilling, so I bought 5 as advised = $46

OEM gasket/filter - $33

2. FSM says I have Command-Trac 231 transfer case.

Yeah, I don't know why the dealership and the service shop I'm using says not to worry about transfer case and differentials.

Just for laughs: the dealership would charge $330 to change those.

This coming week I'm doing:

Lubricate Steering Linkage - 7 zerks
Drain/Refill ATF
Lubricate Steering & Suspension Joints
Oil Change/Filter

All I'll have left with questions then is these 2:

1. Transfer Case - looks like I can do it myself, only 2 plugs.

A. How many quarts of ATF do I need?

2. Front/Rear Differentials

A. How much does the Mopar fluid cost? How many do I need to pick up?

gearlube.png
 
More questions on differentials..

1. What do I use to clean the inside of the cover, says light engine oil or flushing oil?

2. Is actually hand wrenching this back, OK?

3. Will I be fine using a straight edge blade on both sides of the differential to ensure all old ATV is off?
 
The transfer case will take just over 1 quart. 1 liter according to service manual IIRC. (i bought 2 quarts of atf +4 at meijer and used just a little of the 2nd quart.)

It was easy to do, i did it on the ground with no jacks or anything, hardest part was refilling, it was hard to get a funnel to feed down in cramped area. i had to put the ATF+4 into a different bottle (a clean and empty MMO bottle) with a longer and more narrow neck. after that it was super easy. fill it till fluid starts to slowly ooze from the fill hole. the proper level is right at the bottom of the fill hole. same filling procedure with the diffs, fill right up to the fill hole.
 
OK transfer case - solved.

On Differentials SAE 75W-140 SYN Gear Oil

1.2L for FBI AXEL.

So 3 quarts of the gear oil, will do front and back?

I think I'll go to Lowes and just buy an air tool for diffs, can't be that expensive.
 
That Should do it! let me know how it goes, i actually haven't done a Diff fluid service myself yet. Before i bought the jeep the front diff was leaking so The dealer fixed that and changed the fluid. Then I was back at the dealer for some warranty work on a leaking fuel injector and I brought Mobil 1 synthetic gear lube for them to put in the rear since it was already at the shop.
 
A bit of advice,

per he T-case, you will need a allen head to get the two plugs out. I would recommend you remove the top one first, then the bottom in case the top one is stubborn and wont come out.

Also go buy a outboard lower pump that thread onto the qt bottles so you can easily pump the fluid into the t-case. Walmart has em.

I would also suggest you spend on some mopar gray RTV. Really good stuff.

I use Amsoil Severe gear and ATF in my Jeep.

Go buy a turkey baster and do your PS, not sure if you PS takes PS Fluid(probably does for that vintage) or ATF but dont forget that.
 
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