When should you actually replace the filter for the transmission in an auto 4.0

When I look in the manual it never has an interval to actually change the filter, should you ever actually do it or just drain and fill?

There really isn't a filter, just a screen. With that said I will change the filter if I have to pull the pan for any reason. I use full synthetic and just do a drain/refill (part change) every 20k miles.

Unless your tranny pan is leaking and you want to replace the gasket don't bother.
But since tranny pans have a drain plug, my '00 does, it is so simple to replace the fluid on a regular basis that it would be crazy not.

Now you are not going to be getting it all out. Between 4 and 5 quarts will come on but do it regularly enough and all should be good.

I do mine every other year in an even year.

Correct. There was never a maintenance interval to change the screen.

One other consideration, there is a magnet in the bottom of the pan. If you do not know the history of the XJ, I would not hesitate to pull the pan, make a inspection, and clean the magnet. At that time I "would" change the filter and then you should be ready to go for a long time!

Warm up the tranny, drain the fluid into a clean white bucket. You can smell burnt trans fluid, it also changes colors when it gets really hot. I either pour off the old fluid slowly or run it through a paint filter, just to see what is in the bottom of the bucket or stuck in the paint filter. Chunks of aluminum or random stuff can indicate an issue.

I've never found that screen to be very dirty in mine. Even the one time I've had an AW4 with a catastrophic failure.

You never can drain it completely unless you pull the torque converter. So fluid changes are like 30% fluid changes.

Side note: Old trans fluid mixed with acetone makes a decent penetrating oil.

Wanting better I have used Magnefine filters on all my all my vehicles, filters, for many years, for both the automatic transmissions and power steering, placed in the return lines.
https://magnefinefilters.com/NEW-Magnefine-3-8-Magnetic-Inline-Transmission-Filter-R038M-3810000.htm
https://magnefinefilters.com/NEW-Ma...ine-Power-Steering-Filter-R038M-P-3810000.htm

There are several approaches to transmission fluid changes.
I prefer pulling the cooler return line and doing a total flush. It takes a case of fluid but it gets rid of 90+% of the old fluid. Fluid is cheap compared to a rebuild.

lazyxj said:

Wanting better I have used Magnefine filters on all my all my vehicles, filters, for many years, for both the automatic transmissions and power steering, placed in the return lines.
https://magnefinefilters.com/NEW-Magnefine-3-8-Magnetic-Inline-Transmission-Filter-R038M-3810000.htm
https://magnefinefilters.com/NEW-Ma...ine-Power-Steering-Filter-R038M-P-3810000.htm

There are several approaches to transmission fluid changes.
I prefer pulling the cooler return line and doing a total flush. It takes a case of fluid but it gets rid of 90+% of the old fluid. Fluid is cheap compared to a rebuild.

Click to expand...

Going to have to save those links. Thank you.

While I tell everybody not to waste their time on replacing the screen, unless you do have a leaky pan, I am a hypocrite. When I first got my Jeep I did. And the pan was not leaking. But I suffer from OCD (LOL) and I figure I do it and never do it again. Now like I stated earlier I drain and refill every other year. Same with the transfer case and anti-freeze.

Cause just as you pointed out fluid is cheap compared to a rebuild.