So I am on day 3 tomorrow with my new 1998 Grand Cherekee 4.0L. I am working through an alternator issue and then will put er on jack stands for a complete underside inspection. I plan to change ALL fluids since I do not know the previous history. There are 118k on the clock.
Why question to the forum gurus is, what are your fluid recommendations? Would synthetics be an option at this point?
TIA.

 

good idea.

Synthetics aren't really necessary. Whatever the manual recommends is fine. what's important is that you are changing them!! Kudos to you.

What are you gonna do about power steering and brake fluids?

 

I intend to flush the brake system and bleed with Dot 3 brake fluid and flush the power steering as well.
This morning I power-washed the engine bay and did some detailing... Hers looks purdy.

 

I'm less familiar with ZJ's. Do those have the same AW4 transmission as the XJ's? edited: they do not.

If so, I recently went down the rabbit hole (again) about transmission fluid. Its a bit convoluted, but the short answer is Dex/Merc is preferred.

Here is an excerpt from the FSM for my 99 XJ:


Dex IIE/Mercon is no longer available today, but deciphering the progression of transmission fluids shows that Dex IIE/Mercon and was superseded by Dex III, and is now commonly available as simply "Dex/Merc".

Note that "Dexron VI/Mercon LV" is different and is NOT the correct fluid.

Also note that at one point Chrysler released a TSB calling for the use of ATF+4, but there may have been some politics/etc behind this decision, and I believe the TSB was retracted. Some people report issues with ATF+4. I recommend staying away from it.

This is the transmission fluid I use: Valvoline Dex/Merc ATF

Alternatively, if you want the best, I've heard great things about AMSOIL ATF. I wanted to give it a try, but its pricey and hard to get it. AMSOIL Signature Series Synthetic ATF


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The transfer case will be much less picky about what fluid you use. Here is the call-out in the FSM:




Pretty much what I take from this is that the transfer case can use the same fluid as the transmission.

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I'm less informed/**** about other fluids on the vehicle. I am a big fan of synthetic fluids. I have used Rotella T6, Mobile 1 high mileage, and also Pennzoil Ultra Platinum high mileage engine oils. Its oil. They're all good. Buy whichever bottle is your favorite color.

Awhile back I dug into the coolant spec on these vehicles. IIRC, the OEM spec is a HOAT coolant (G-05?), but I remember reading it really doesn't matter and standard green ethylene-gylcol will be equally as safe, but maybe with a shorter service interval. Whatever you use, make sure to only use distilled water to mix and not tap water.

I can't speak much to the other fluids on the vehicle other than I recommend running a -140 weight gear oil in the rear end. This is called out as recommended for "severe conditions" in the FSM, which can be defined as something as simple as driving in hilly terrain.

 

ZJ does not have an AW4 it has a 42RE that takes ATF4.

 

10-4. Edited my post.

 

Thank you for the reply. I am delayed in getting the Jeep up on stands today as I was doing interior repairs and details. I have heard good things about Rotella. I believe it has a good dose of zinc additive that folks seem to like.
I agree on the 140 weights for the diffs and green antifreeze. Will go with the recommended factory fluids for the trans and transfer case.
Thanks again.