CaptainXL said:
What's this preoccupation with the transmission filter? 90% of transmission failures are due to overheating and a lack of fluid change....not filter change. The filter will last a long time.
A trans flush utilizes solvent to dissolve deposits from the torque converter and valve bodies and filter. It is done in the direction of fluid flow.
I had a flush done at the GM dealership and my fluid is pink with no debris in it. So the filter is doing just fine.
In reality doing a flush through the cooler lines yourself or even just a partial pan drain and fill could be more hazardous rather than using the solvent based machine method the dealer uses. If solvent isn't used then something could flake off later on down the road. Better to flush it with solvent then not.
not so much a preoccupation, but an observation.
Gm recommended service at 100k miles is to drop pan, clean out, and change filter, then refill fluid to the proper level. part of this is to examine the pan to see what the residue looks like. (fine particles are ok, metal shavings not so much)
my pan had a nice coating of particulates after 40k, and the magnet had a thick coat of magnetic particles which needed to be cleaned.
if you forward flushed, particulates which accumulated in the pan are either still in the pan, or stuck on the dirty side of your filter. you may not have any problems, but this can reduce the capacity of the filter. leaving the stack of magnetic particles on the magnet also increases the surface area and decreases the magnetic field available to catch more from the fluid. (not a huge reduction, but some...) the magnet is there to make life easier on the filter.
I am not convinced that your dealer flush uses any solvent other than the new fluid. more of a fluid exchange. they might put some additional solvent in the trans before the exchange, but this cannot be hugely different than the fluid. (how would it be removed?) a small amount of whatever solvent they use will end up mixed with the new fluid, so nothing too caustic is advised.
I looked around and all the machines I see on the web are fluid exchangers. the GM service manual discusses use of a flush and flow machine to use to verify the radiator mounted trans cooler allows enough flow for effective cooling. if you can post a link to a machine that has separate container for solvent to flush transmission out, I would be happy to learn of it.
You are welcome to skip the drop and filter change if you like. not sure how many folks have had blocked trans filters which cause problems, or had filter failure which allowed bypass of particulates through the transmission.
the most conservative path would be to change the filter, clean the pan and exchange the fluid. (after use of a "flushing solvent" if desired.)
