Motor Oil in AW4?

I am considering buying a Cherokee from a friend but there's a problem. Someone changed the fluid in the transmission and put MOTOR OIL back in.

It's a '92 with AW4 transmission and around 122k miles. It was probably driven for less than 100 miles with the motor oil in the tranny. Of course, the transmission started acting up and not shifting correctly. The fluid has since been changed back to Decron III but I'm told the tranny still shifts funny.

How much damage was done? What problems should I look for? Will the tranny need replaced or will it be okay?

Thanks in advance for your knowledge and advice.
Doug

(PS I did a couple different searches on this. After 25+ pages I gave up.)

no way to be sure it will be okay. were it me, i'd opt for taking it somewhere where they have the machine that will pump out ALL the tranny fluid. then put a drain plug on the pan and keep changing it yourself till you know all traces are out.

Let me guess it is slipping. The cluches in the auto need a certain amount of friction in the fluid to properly operate (why the AW-4 dosn't like synththetic tranny fluid) at worst the oil has contamanated the cluch disks, and they will need replaced. At best repeated flushing will wash off the oil soaked cluches, and it will be good to go.


IMHO if the price is right pick it up swap the tranny for a junk yard unit. Then eather use the other one to lean how to rebuild one, or have it rebuilt then sell it.

scoobyxj said:

IMHO if the price is right pick it up swap the tranny for a junk yard unit. Then eather use the other one to lean how to rebuild one, or have it rebuilt then sell it.

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Yea right because its so easy to swap tranny's back and forth.

Sorry to say, it's probably junk. I've seen trannies roached instantly by the wrong type of fluid let alone motor oil.

How was the fluid changed? A full flush or just drop the pan? If it was just a drop of the pan, then more than 50% of the fluid is still motor oil.

Trans fluid is just motor oil with a different additive package, BUT a very very different additive package. So no one would be surprised at either outcome, flush out any remaining motor oil, will probably take a full flush and several full tranny fluid & filter changes to get all the traces out and the thing may run fine, OR the tranny may be shot in a few more miles.

As far as the tranny slipping? Most ATF has friction modifiers to be more slippery than motor oil, so the clutches engage more smoothly, I would "THINK" motor oil would let the clutches engage faster. BUT, motor oil would not make good hydraulic fluid to operate all the hydrualics in the tranny, so not only would you get poor operation of the hydraulic valving and servos, clutches/bands would engage weird as well. And that could cause damage.

I'd walk away, then come back a couple days later when no else bites because of the tranny. Argue that the tranny is most likely going to fail and cost you $1500 at least to replace, that they need to come way down on the price for you to take the risk of buying a car with a tranny that will most likely need replaced.

I think he just dropped the pan when he changed the fluid. The local off-road guys don't know of anyone around here that has the tranny flush machine anymore. I would plan on flushing atf out the tranny cooler line. I'm gonna test drive the Jeep tommorrow and see how it acts.
Thanks for the input.
Doug