Why, different trans? I allways wondered if I could use that instead the +4, which is expensive and sometimes hard to find.

 

XJs have the Aisin Warner AW4 auto transmissions, ZJs have a Chrysler 4 speed auto 42, 44, or 46RH/RE.

 

besides the different fluid what's so different about the transmissions? I would think that Chrysler would use the same tranny and save money through economy of scale.

 

Chrysler did not design or build the XJ transmission. It's from a different company, Asin-Warner. It's used in a bunch of cars, including Toyota trucks. It's a beast of a transmission.

At one point, Chrysler DID start recommending ATF+4 for that transmission, and it caused a lot of problems. Asin-Warner has always recommended Dex/Merc.

Fluids in transmissions are normally critical. Don't ever substitute some other kind. The WalMart ATF-4 is fine, and is the cheapest I have found. I use it in my Grand (WJ). Nothing but Dex/Merc in my XJ.

 

The AW4 definitely is a beast! Think Toyota trucks used by insurgents in the mid-east! Do you think they EVER get serviced? Maybe to add fluid to make it go.

Chrysler tried using ATF+4 in the AW4 to simplify dealership inventory, but they found it causes clutch chatter. The only thing they DID simplify was to use the same fluid the trans uses in the t/case of each model, until things got complicated. Think 249, 247, and the electronic shift ones.