Weekend "to do" list...
 

So it looks like I'm gonna be buddies with the 91 for a while. I had a 99 that a buddy of mine who runs a jeep dealer was gonna whole sale to me, but some crap went down with the bankruptcy court and it got taken back... So I have some stuff I need to take care of on the red 91. First of all I have a bad grinding noise when I am making a sharp left turn from a dead stop. I am pretty sure that it's the u joints, so I'm going to put some new ones on. I am also planning on changing the diff fluid in the front while I'm at it to eliminate that as a possibility. I also have some really brown tranny fluid that I am planning on changing. Just dropping the pan and replacing the filter and gasket then adding new fluid. Is there any risk involved doing this type of change on a 21 year old jeep with 192k miles? I'm just worried that the gunk in the tranny is all that's holding it together, although it does shift much better than my 96 2wd did. Anyway, that is what I am hoping to accomplish this weekend along with fixing my brake noise. My main question was about the tranny fluid. Thanks for reading!

I'm no mechanic but I wouldn't think simply draining the fluid, changing the filter and filling with new fluid would be a problem. I wouldn't flush it though at that age and mileage. I say go for it! Especially if it's that nasty of a color.

Drain and fill repeatedly over the course of the next year. Don't want to change the tranny fluid all in one shot at that age.

So probably a Better idea to do it gradually?

Yes. Drain what is in the pan; it will be between 3 and 4 quarts. Drive for a while, then repeat until fluid stays red.

When fluid stays red in color, if you think filter maintenance hasn't been done, it would be a good idea to drop the pan and replace (or at least clean) the filter. It's really just a screen.

Use Dex/Merc III compatible fluid here. I would NOT use ATF+4 fluid, no matter what the parts store says. A while back Chrysler blessed the use of this, but it also has been directly tied to "slippage" in some (not all) AW4 transmissions. With absolutely no risk using Dex/Merc III, why would you take the chance? That is the fluid that the AW4 was designed for and is perfectly adequate for a long life for this transmission.

So drain EVERYTHING in the pan and refill?

Yup, there's a drain plug on the pan. Pull it and wait till it stops. Replace through the dipstick tube with the same volume of nice red Dex/Merc III.

The dipstick was stuck to my tranny pan and I had to unbolt the dipstick to lower the pan to change the filter. Plus there are like 19 10mm screws on the pan and 6ish on the filter. If it's not leaking, I'd just change the fluid a couple of times with transmission fluid from Walmart and call it a day. Don't use synthetic, it slips and you actually lose gas mileage.

It does shift better with new fluid.

Just a noob...