Hi y'all, after scouring the forums, most people seem to agree that Dex III is the fluid for an AW4. My stock 99 XJ's AW4 was rebuilt at 172000 mi with ATF4, and I've since put 41000 miles on it, reaching 213000. I did not know that this transmission needs to be serviced every 30,000 miles; I've only been watching YouTube videos to service parts as they break. I haven't noticed any significant symptoms of a failing AW4 on my XJ, but I have noticed that the fluid sometimes looks clear on the dipstick between the first safe line and elevated line, so I've had to top it off.

I'm thinking I should just make the switch to Dex III as a member from this thread states "just put the Dex/Merc in it" https://www.cherokeeforum.com/f2/mix...x-merc-148916/

My understanding thus far has been that it's not generally a good idea to do a full flush of transmission fluid for the AW4, and instead to drain over time.

So is all I need to do, I ask especially because it's been 41k miles, is drain 4 qts of ATF4, then add 4 qts of Dex/Merc, and repeat once more? Or do I need to do this doing 2 quarts every 500 miles?

Thanks guys, I've been wearing myself out being afraid to mess up as I've already had the transmission fail on me the day I got the XJ (context: it was my first car and still is from parents who were about to trash it, tranny had no fluid in it, and I was not at all familiar with cars at the time)

 

Mixing ATF+4 with DEX/MERC is not a good idea, I would drain the fluid and use ATF+4 or do a fluid exchange (not to be confused with a flush) and use DEX/MERC. Imo I would stick with ATF+4 if the transmission is shifting fine. There's nothing wrong with ATF+4, the problem is mixing it with DEX/MERC. As a side note ATF+4 is full synthetic so every 30k is too early (unless you're off roading or towing).

 

I'm about to switch out all of my lines and completely drain my transmission. Was going to go Mopar ATF+4. I don't think the transmission was ever serviced. What else should I do, I'm not going to do a flush seems to also jack up a transmission.

 

If it was rebuilt the fluid is fresh (well it has 41k on it). No rebuilder worth his salt wouldn't run %100 fresh fluid after rebuilding it. There's nothing else to do, the filter is just a screen so no sense changing it. I would recommend adding a transmission cooler if you can these AW4 transmissions run hot and it's cheap insurance. It's not a necessity, I don't even have one on mine and it has 230k and shifts great, but since you're changing lines anyways you might as well.

 

use dex/merc lll, not atf4

 

What about my transfer case? What do I use for that?

 

DexIII/Merc in that too

 

It all depends on what you mean by, "flush".

Flushing a transmission can be done several ways, and only one of them is bad.

Some shops offer a 'power flush' which uses a high pressure pump to flush the fluid out, often in a reverse flow.

THIS is what can kill a transmission.

Other shops hook it up to a machine and run the engine, letting the transmission's own pump move the fluid. This will NOT hurt your transmission. It's actually very good.

You can do the same thing yourself at home, and doing so has rescued more than one transmission. See my sig, #3, for more on that.

 

Yep this is the way Valvoline instant oil change does it. I asked them them specifically what method they used and they use the transmission pump to pump new fluid out and new fluid new in. The transmission on my mgm shift great, so I'm happy! They also use their full synthetic fluid which imo is the best there is.

 

I appreciate the input, you guys.

I guess I'll stick to ATF4 for now then for simplicity. Is there an interval you recommend for changing the fluid?

Thanks.

 

If you are going to change %100 of the fluid use DEX/MERC, if you're just draining the pan stick with ATF+4 because mixing fluids is bad. Intervals wise I like 50k for full synthetic BUT I don't tow or do any off roading. If you tow or take your' Jeep off road change it every 30k. If you use conventional just follow what the owner's manual says.

 

I'm going to stick to the pan draining for simplicity's sake, and since I don't tow or take this 2WD that is my DD off-roading, I'm glad to hear 50k works for you and I will stick to this method, keeping an eye on the dipstick.

One more question for clarity's sake. For the pan drain method, should I be draining 2.5 quarts and adding 2.5 (or up to dipstick), driving for some 500 miles and then repeating until 8 qts have finished?

Or is it better to drain, fill as much as came out (est. 2.5 qt) shift through the gears, check the level, repeat until 8 qts all at once once 50k interval has been reached.

Thanks again.

 

I would have to look at the owner's manual to see what it suggest. Some vehicles only require draining the pan every 50k others require all of the fluid to be changed.

 

No!

Use Dex/Merc only. That is what the manufacturer calls for. Chrysler started recommending their fluid at some point, so a lot of manuals say that, but they are just flat wrong.

Asin-Warner, who makes this 4 speed transmission (AW4, get it?), says Dex/Merc.

Use Dex/Merc.

 

The transmission is already filled with ATF+4... Since OP is not draining %100 of the fluid he/she should stick with ATF+4. Mixing transmission fluid together can and will damage the transmission. Chrysler specifically says to never mix ATF+4 with Dexron or Mercon! There's plenty of people that use ATF+4 in the AW4 with no ill effects, sure there's people that claim "ATF+4 killed my transmission" but who knows if it's the fluid that killed it or if it was neglect. Toyota uses T-IV in the A340E/F (AW4) so if you want to listen to the manufacture use that fluid because that's what their TSB says.