Kymasabe

I have to do trans service on my wife's '04 WJ, was wondering if ATF+4 was still safest choice or if there's a better option.

wingless

The only fluid that should be used in the 42RE transmission is ATF+4.

Kymasabe

By the way, some of the information at that link is incorrect , I wouldn't trust all that I read there. Quick glance said 4.0 liter motor takes 5 quarts of oil (takes 6) and AW4 trans takes ATF+4 (uses dex3).

wingless

Fine, all documentation states that ATF+4 is the only fluid appropriate for the transmission.

Muddz

From an OEM 1995 ZJ service manual.

RECOMMENDED FLUID

The recommended and preferred fluid for 42RE transmissions is Mopar ATF Plus, type 7176.
Dexron II fluid is not really recommended and should only be used when ATF Plus is not available

Plus 4 is the most recent, improved version, replacing earlier versions of ATF Plus should be used in the 42RE.

I don't use ATF+4 in my XJ's AW4 I use either Dex III or Amsoil ATF.

gon

My AW4 takes Dexron3 and only Dexron3

dave1123

Yeah, my FSM says using Dextron in the 42re will result in clutch chatter. The FSM for my XJ states use Dextron IIE/Mercon in the AW4.

SteveMongr

The AW4 was made by Aisin-Warner and specifies Dexron3 only (it is not a Chrysler transmission).
The 42re is a Chrysler transmission and requires ATF4.

Muddz

The problem is some Chrysler Dealerships have recommended to individuals and transmissions shops to use their Mopar ATF+4 for Jeeps using an AW4 transmission.

I had this problem just over 10 years ago when I purchased an XJ and took it into a transmission shop to have the old ATF passively pumped out and replaced with new ATF. The transmission called their local Jeep dealership and asked for the correct ATF to use in a 98 XJ with AW4 transmission. They were told to use Mopar ATF+4 which they did. At the time I didn't know much about the XJ or it's transmission and thought everything was ok.

However later on the XJ started to shift harder not as smoothly as it had before. After reading up on the AW4 and what ATF it was original recommended and designed to use I then pumped out all the old ATF and used Amsoil ATF which is Dexron III Mercon compliant ATF and covers many different types of ATF. I then added an external transmission filter as the AW4 doesn't really have a filter but more of a screen (with no service interval) that's really never replaced other than when the AW4 is serviced.

I prefer Amsoil ATF as it has a longer service life, i.e. longer intervals between oil changes. It's rated for a min. of 100,000 miles that it won't oxidize and fail (as long as it's doesn't become too dirty.) There have been test in service vehicle such as taxis, trucks, etc. where Amsoil is still viabile ATF after 180,000 miles.

One problem with standard ATFs is they potentially oxidize, break down and become dirty and will only last ~25,000 - ~30,000 miles after-which the oil breaks down and can no longer perform.

The only reason I can think of why Chrysler recommends ATF+4 for a AW4 transmission is because Chrylser no longer has a Dexron / Mercon ATF (which they did at one time), and their ATF+4 replaced all their older ATFs they had at one time marketed and recommended under the Chrysler logo.

Some dealerships may have caught on however often the dealership goes with what is officially recommended by Chrysler.

Hatsuwr

I believe TSB 21-014-07 is the most recent regarding this topic:

http://www.wjjeeps.com/tsb/tsb_wj_2101407.pdf

Which, unfortunately, is slightly ambiguous.

I use Royal Purple Max ATF since it is claimed to be compatible with all other fluids, and from my experience Royal Purple has high quality products. A bit pricey, but not a big deal with how infrequently transmission fluid is changed.

wingless

According to that document:

NOTE: **AW-4 (Asian Warner) transmissions are now included in this Service Bulletin. ATF+4Ž is recommended for AW-4 (Asian Warner) transmissions**

Hatsuwr

Yup. Wonder what caused the reversal. More time for testing? Or maybe the cost saving from moving toward a single fluid made it 'good enough'?

Muddz

That document is dated October 16, 2007, earlier TSBs test results are ATF+4 is not recommended for Chrysler AW4.

I'm not certain exactly when all Chrysler Jeeps using a AW4 actually became out of warranty, but this became true in 2007.

In 2007 Chrysler changed their miind and decided that ATF+4 can be used in a AW4 trans, perhaps new testing was done with different compatiblity requirements. The AW4 was originally designed using a Dexron/Mercon ATF.

ATF+4 is a synttheic ATF and can withstand more heat than a Dino Dex\Merc III. However there are now synthetic and synthetic blend ATFs compatible with Dex/Merc III that are similar and better than ATF+4. One I know of is Amsoil ATF. Also Mobil One ATF is compatible with Dex/Merc III, however both ATFs are more expensive than ATF+4 which ranges from around ~$4.50 to ~$8.00 per quart.

Personally if on a budget I would go either with something like a Valvoline Dex/Merc ATF or a Valvoline MaxLife Full Synthetic Multi-Vehicle Automatic Transmission Fluid.

Valvoline Dex/Merc doesn't state it a synthetic blend only that it's formulated from premium base stocks and advanced additive tech. Also it suppose to have low temperature fluidity.

Maxlife: a synthetic ATF is engineered with a unique blend of viscosity modifiers and base oils to provide better oil flow at low temperatures and greater film protection at higher temperatures

I would probably go with any Synthetic or Synthetic blend that's compatible with Dex/Merc over ATF+4.

The problem I had with ATF+4 in my 98 XJ (AW4) is it effected shifting, XJ started not to shift normally, shifting was harder and not good smooth shifting as when using a Dex/Merc ATF.

ATF+4 is specially formulated to ensure optimal performance in Chrysler automatic transmissions. Its unique additive package provides the proper frictional properties, excellent low-temperature fluidity and dependable wear protection required in applications where a Chrysler MS-9602 type fluid is recommended.

The AW4 isn't a Chrysler transmission it's an Asian Warner Transmission designed to use Dex/Merc ATF. When looking at ATF+4 I don't see anything online that it's compatible with transmissions that use Dex/Merc ATF.

Though ATF+4 has better specs (shear, heat range, etc.) than specs for the original Dino Dex/Merc, I'm reading online that a Dexron III or Mercon ATF is not going to be compatible with Chrysler ATF+4 or ATF+5. I'm uncertain how Chrysler was able to ever recommend it for the AW4.

There are multi-ATFs that are compatible with both ATF+4 and Dex/Merc such as Amsoil ATF that is going to be significantly better than ATF+4 which isn't a bad ATF, I use it in my ZJ with a 42RE transmission.

Another is Mobile One Synthetic that's rated for Dexron/Merc .with a cost similar to ATF+4 Imo is going to be a better synthetic ATF to use with the AW4 transmission. Chrysler can only endorse and recommend fluids and lubricants that it actually markets under the Chrsler / Mopar logo. Chrysler no longer markets a Dexron/Mercon type ATF it had at one time long ago.

(Mobil 1 Synthetic ATF)

General Motors DEXRONŽ IIIH
General Motors DEXRONŽ IIIG
General Motors DEXRONŽ IIE
General Motors DEXRONŽ IID
General Motors DEXRONŽ II
General Motors DEXRONŽ
Ford MERCONŽ

https://mobiloil.com/en/automatic-tr.../synthetic-atf

dave1123

If Fiat Chrysler is telling dealerships to use ATF+4 in the AW4, they are going to use it. The reason being is if the transmission fails and they used anything else, the dealership will have to eat the bill for the repair. It all boils down to the bottom line.

My 2000 WJ with the 42re just cleared 245K miles and never had anything but Valvoline ATF+4 in it beside the factory fill. It's been changed with a filter on average every 50K miles and is still shifting solidly and normally even hauling heavy loads weekly. The only additional service it's had was a couple of solenoids and a governor pressure sensor. No line pressure or band adjustments either. What more can you ask for?

Muddz

I don't have anything against ATF+4 in a transmission designed for Chrysler's ATF+ but I don't believe it's good for the AW4 transmission. People have been using Dex/Merc in a AW4 for more than 300,000 miles without any problems. I'm not certain if ATF+4 actually does any damage to a AW4, my experience is it noticeably effects the shifting. Potentially after so many miles possibly can effect wear of the transmission.