post #1 of Old 02-03-2009, 11:49 AM Thread Starter
87warrior
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Opinions on replacing AW4 transmission fluid

I finally have a Jeep with the AW4 transmission and have a concern. It is in a '92 with 185k on the odometer. Due to the fact the truck is 17 years old I am planning a fluid change for everything.

Should I change the fluid/pan filter in the AW4? If so, with what?

I recall that some folks suggest not to change the ATF in an auto with a lot of miles on it. Please school me on this.

Thanks


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post #2 of Old 02-03-2009, 01:03 PM
98muddyjeep
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you should be ok changing the fluid and filter since when you drain the pan you only get half the fluid the other half is in the converter so the new fluid will mix with the old so you will be ok.Do not get a trans flush that can cause more problems than its worth.

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post #3 of Old 02-03-2009, 02:14 PM
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Quote:
Originally Posted by 98muddyjeep View Post
you should be ok changing the fluid and filter since when you drain the pan you only get half the fluid the other half is in the converter so the new fluid will mix with the old so you will be ok.Do not get a trans flush that can cause more problems than its worth.
Ditto on all of the above.

Changing the filter is a bit of a paradox though. I don't think I've ever read where someone's changed the filter and looked at it and thought that it needed to be replaced, but at the same time, everyone, myself included, has always felt better having replaced the filter, even if it looked perfectly fine.

Some places are now offering a non-pressure flush, where the transmission itself cycles all the fluid -- it's not forced through under pressure. That's the only type of "flush" I'd ever consider doing, and you can do that yourself with a couple of buckets and a bunch of fluid.

Be sure to use Dex/Merc III type fluid and nothing else. It may be a "Chrysler" vehicle, but it does not have a Chrysler brand transmission.

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post #4 of Old 02-03-2009, 02:24 PM
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Quote:
Be sure to use Dex/Merc III type fluid and nothing else. It may be a "Chrysler" vehicle, but it does not have a Chrysler brand transmission.
Chry Co doesn't manufacture the AW4? Hmm, didn't realize that.

I use Dex/merc anyway.

What I have done with my 99 XJ is simply change it frequently using the handy-dandy drain plug. I gleefully use it as most all my mechanical experiance is with Chevrolets and in most cases you have to drop the pan on them. It's a real PITA.

Last summer when I bought my XJ the fluid was nasty, but the trans shifts fine. I went ahead and changed the fluid six times over the course of the late summer and early fall. In some cases I even got in the XJ and for a VERY short period of time would start it up and allow the pump to force some more fluid into the pan. I brightened the shade of red considerably using this process, and I never had to lower the pan.

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post #5 of Old 02-03-2009, 03:09 PM
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Quote:
Originally Posted by kadetklapp View Post
Chry Co doesn't manufacture the AW4? Hmm, didn't realize that.
Nope. The AW4 is made by Aisin AW (though it ceased to be called Aisin-Warner in 1987, coincidentially the same year that Jeep started using the transmission, and is now just Aisin AW). If anything, it's a "Toyota" transmission because it shares a lot of parts with the Toyota 450-43LE that was used in I think the Supra and 4Runner. Toyota also owns a majority stake in the company, but Aisin AW provides transmissions to just about every car maker.

http://en.wikipedia.org/wiki/List_of..._transmissions

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'95 XJ, RE 5.5", 35" MT/Rs, D30 w/hubs & ARB, D44 w/Detroit, 4.56s, C4x4 bumpers, etc, etc.
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post #6 of Old 02-03-2009, 03:30 PM
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Wow I'll be darned!! Must be why the label on mine says something about Japan....

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post #7 of Old 02-03-2009, 03:52 PM
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Heh-heh, it's somewhat ironic that something considered one of the most bullet-proof parts on an XJ is actually made in Japan.

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'16 JKUR Hard Rock, RE/Synergy 3.5", 37" GY MTR/Ks
'95 XJ, RE 5.5", 35" MT/Rs, D30 w/hubs & ARB, D44 w/Detroit, 4.56s, C4x4 bumpers, etc, etc.
'00 TJ, SOLD, wife's, RE 4.5" long-arm, 35" MT/Rs, D30+OX, D44+ARB, 4.88s, full cage, winch, C4x4 & Jeeperman bumpers, etc, etc.


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post #8 of Old 02-03-2009, 04:07 PM
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By the time you have the pan down and the filter out, you should be replacing the filter. It's cheap and the cost of the fitler and gasket kit isn't a whole lot more than the cost of just the gasket, if you can even get it. Use only Dex III in the AW4. May consider the transmission pump flush, but, as Jason said, do not use any machine that flushes under power.

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post #9 of Old 02-03-2009, 04:43 PM
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Originally Posted by 87warrior View Post
I recall that some folks suggest not to change the ATF in an auto with a lot of miles on it.
I've heard that before as well and I couldn't disagree more with it. It defies logic to leave old, dirty, worn out, burnt tranny fluid in a vehicle.

The AW4 has a drain plug on it. You can change out approx. 3 quarts of fluid by just draining the pan. Do it a few times over the next few months if the fluid looks bad or smells burnt.

If you're ambitious, drop the pan and clean or replace the filter which is basically just a screen. Most important thing though is to get some fresh fluid circulating.

Use Dex III fluid.

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post #10 of Old 02-03-2009, 07:12 PM Thread Starter
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Thanks for the help guys. This whole Auto thing has me running in circles!

Should the Dex III/Merc III fluid available at the local auto parts store? I know synthetic is deemed a "no-no" on a high mileage AW4.

I think initially I will simply drain and replace the fluid. After 6 months I will replace the filter and fluid.

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post #11 of Old 02-03-2009, 07:20 PM
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Dex/Merc III is a regular trans fluid, it should be available anywhere that sells vehicle fluids.

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'16 JKUR Hard Rock, RE/Synergy 3.5", 37" GY MTR/Ks
'95 XJ, RE 5.5", 35" MT/Rs, D30 w/hubs & ARB, D44 w/Detroit, 4.56s, C4x4 bumpers, etc, etc.
'00 TJ, SOLD, wife's, RE 4.5" long-arm, 35" MT/Rs, D30+OX, D44+ARB, 4.88s, full cage, winch, C4x4 & Jeeperman bumpers, etc, etc.


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post #12 of Old 02-03-2009, 07:55 PM
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why shouldnt synthetic dex/merc be used on a high mileage AW4?
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post #13 of Old 02-04-2009, 05:31 AM
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Originally Posted by 87warrior View Post

Should the Dex III/Merc III fluid available at the local auto parts store? I know synthetic is deemed a "no-no" on a high mileage AW4.
anyone have a reason for me?
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post #14 of Old 02-04-2009, 07:28 AM
tjwalker
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I have used synthetic transmission fluid (Amsoil) in my AW4 since the first service. I also use synthetic fluids in the differentials and transfer case. You will find many differing opinions on this. In my opinion, there isn't a right or a wrong answer.

There are people that claim that the synthetic fluid is actually "too slippery" for the AW4 but I haven't seen enough actual failure analysis to support that claim. Just because a transmission fails early and that individual was using synthetic doesn't necessarily mean that synthetic fluid was "root cause" of the failure. A certain percentage of anything as complex as a transmission will suffer premature failure no matter what fluid is circulating in it.

The AW4 certainly doesn't require a synthetic; plain old Dex III is much cheaper and works just fine with plenty of evidence of AW4 transmissions going 200-300k on conventional fluids.

However, there are a number of reasons that people "choose" to use a synthetic. To each their own. Use the SEARCH function for tons of light reading on this. No need to reinvent the wheel.

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post #15 of Old 02-04-2009, 08:22 AM
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I use plain Dex/Mex just because it's plentiful and cheap.

Some people believe that putting fresh fluid in an old transmission causes it to fail. The fact is, if the trans is slipping after fresh fluid, then the trans has been on it's way out for a LOOONG time. If it does slip, and you need to get a little more life out of it, then you can use a friction modifier in the fluid to help get "grip."

That's all it is. The old gritty fluid causes the stripped transmission to get better "grip" and when new fluid is injected, it starts to slip.

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