2000 xj 4.0 aw4 np242 160k original miles on everything

Is Mercon 5 a good tranny fluid to run on an aw4?

Long story short blew tranny lines at work luckily I work at the ford dealer so I fixed the lines however I lost about 3 quarts of fluid and topped it off with the only stuff we had in the house, merc 5. All data says dextron 2 and Mercon auto transmission fluid are acceptable however I do not know if merc 5 has any difference, drove about 20 miles so far on it, so far seems fine smooth shifts, just don't want to blow it up as it is my DD.

 

Shouldn't hurt anything. At the place I work we normally use C-6 for everything, I believe that rates as a 80/90 gear/hyd oil.

 

Original fluid is Dextron III/Mercon. That is what GM transmissions used.

The Ford stuff has different additives in it. Probably would have been better to get O'Reilly's to deliver some Dex III to you.

 

should I drain the tranny and give it 8 quarts of dex 3 instead of the 50/50 dex3 merc5 mixture?

 

If you just drain it, you will only replace about half of it, since you wont drain whats in the torque converter. So, all you really do is dilute it.

If you really want to get all the guessing out of this, do a forward flush and that way replace all the ATF in a few minutes, refill with Dex III (the Dex/Merc is no longer made I think, so any Dex III spec ATF will do) and be done for the next 30K.

 

Mercon and Mercon V are not the same fluid, or compatible. Apparently there's an "additive" to "convert" Mercon V to meet Mercon specs.

As stated, the original specification for the AW4 was Dexron II/II-E/Mercon (I), later upgraded to Dexron III/Mercon. Volvo and Toyota only recommend Dexron III/Mercon/JWS 3399 fluid in the AW4. Chrysler did too until they stopped carrying the correct fluid entirely when they warranty period ended.

Dexron III/Mercon formulations are still available, with the license no longer being renewed however manufacturer's can't use the name or get it certified. But it's still the same goo. Anything sold as Dex/Merc or D/M is what you want.

There are many good fluid choices out there, from Walmart's SuperTech to Valvoline MaxLife D/M and Castrol Transmax Multi-Vehicle.

You don't need to look for whale oil, but when choosing a fluid avoid anything that meets ATF+4, or brand new Mercon or Dexron specs. They are typically ultra-thin resource-conserving fluids that do not have the required friction modifiers. Damage from clutch chatter or just plain slipping will occur.