I've had transmissions flushed with no problems...ever. I change the filter, fill it up with the cheapest atf I can find and get it promptly flushed.

It's always been done by hooking up to the cooler lines and the engine does the pumping...just like it normally does.

I'm not clear how replacing old fluid with new will kill a transmission.

I've seen transmissions killed by too much heat, stress and even cold. I've never heard of one being killed by replacing old fluid with new.

I regularly replace all the fluids in my vehicles. It has served me well in the past and I'll continue to do it in the future.

 

The flush machines I've heard/read about didn't use the transmission's pump, it used an electric pump and among other modes, back flushed the filter which won't be near as good as installing a new filter.

 

Engine Flush is a "whole nother country".
I've seen them work miracles on poor running smokers...especially on Fords, which tend to have larger oil journals.
But it's still major surgery, IMO.... and a last resort.

Are we maybe getting confused here, or is it just me. There are machines that 'change out' tranny fluid while the truck is running.
And there are apparently Flush machines also??

RJ

 

The machines I've used don't 'pump' at all. They are, in fact, merely a reservoir...new oil goes out of the bottom, old oil goes in the top...all done by the transmission itself, and not backflushed.

 

I can see that with your filter change...out with the old and in with the new. Is there a way to tell when the change out is complete?

 

The machine has a reservoir split into two sections, with the old and new separated by a visible moving piston. The old oil goes in the top and it pushes the new oil out the bottom. It's basically in line with your cooler.

I change the filter first. I reckon that any particles will have long been picked up by the filter or left in the pan so I get a chance to do an inspection.

Dirty fluid will be circulating through the new filter but particles large enough to be caught, won't be.

ATF is a lubicant but it still has to work with the pad surfaces to enhance friction, so it does double, somewhat contradictory duties. Over time, heat, evaporation, oxidation, shearing and whatever else your fluid goes through will degrade some of the properties.

My preference it to do a full fluid swap instead of just a pan capacity/filter change every few years or if I smell any burning. I've had good luck with the process and it has never caused me any problems.