That's bunk about fluid replacement.

Kinda like having a professional teeth cleaning causing tooth loss.......

I can't imagine particles in the fluid being a good thing, if the clutches are badly worn grit in the fluid won't help much or for very long (would be similar to the old used car dealer "trick" of sawdust in the fluid) and loose particles have the potential to score bearings or clog/damage the valve body. Usually what I hear about changes is to avoid a pressure flush which can knock "gunk" loose causing fluid passages to be clogged (especially if the fluid hasn't been changed in a long time), but that a fluid change (either by drain and fill or a "flush" through the cooler lines using the transmission's own pump) is beneficial.


My AW4 has a little over 220k mi on it (I put the filter and cooler on at around 215k mi) and I haven't had any issues with this setup, I also changed the fluid not long after I got the Jeep (with a total of 5 drain and fills spread over about 1,000 mi., 3 would have probably been sufficient but DexronIII is cheap).

Anything on the interwebz is the gospel, no?

The problem isn't fluid replacement.

The problem is that some shops offer a "transmission flush" that consists of disconnecting the cooler lines and hooking them up to a machine, which then flushes the trans with high pressure. It's basically pressure-washing the interior of the trans.

On an older trans, this can dislodge things, resulting in clogs later. Not good!


Just replacing the fluid with the correct, CLEAN fluid is a good thing.

Particles in the fluid are not "necessary", they are a PROBLEM.

Thank you masses of CF for once again replacing my ignorance with real facts. Now I know!

And knowing is only half the battle...

........and some tranny shops use a flush machine that utilizes the vehicles tranny pump to circulate old fluid out/new fluid in....in other words, no high pressure is used.

I am curious.. what pressures are going in and out of the trans cooler lines? I know internally the trans uses high pressure... but given that coolers can be attached with simple hose clamps...

I don't have the actual specs. (maybe someone on here does), but I've heard around 20-30 psi on the cooler lines.

The sawdust goes in the differential, not the transmission. lol

Yeah, which works better, redwood, or pine? We need to KNOW!

Didn't redwood get the banned illegal tree hugger thing? Only pine available now I guess, not worth the prison time for the black market redwood stuff, lol.

Where'd ya get the T fitting?

Most any hardware store will have a 3/8" brass T with the nuts and compression fittings (ferals).

I believe Lowes, any hardware store should have them in the plumbing section.

ok, so that's all it is, a brass T, that works.