Here is the truth about "Flushing" transmissions.
Most companies that flush transmissions use the machine that attaches to the cooler lines. All this does is mix new fluid with old and if you add enough new, it will finally change color to red. With this type of flush, the shop does not drop the transmission pan for inspection and this is where the problem starts..... I manage a transmission shop in Colorado and we used to throw out the salesmen that came in trying to sell us this type of machine. All they talked about was how much money that we could make...not if the service was any good or not.
Now for the good news....
You should service the transmission about every 25,000 to 30,000 miles and it is a MUST to replace the transmission filter everytime you service the transmission. When we do a transmission flush, we first drop the pan to do a check on the condition of the transmission . You can look in the pan to see what color the fluid is, if there is metal on the magnet and if there is clutch material in bottom of pan. If they is a lot of "junk" in pan, you DO NOT want ot flush the trans. The machine will do its job and that is to clean the inside of the trans.... if the cluch packs are being held together by this junk, the transmission may not work correctly after you get done...but this is not the machines fault...its doing its job. The fault is in the tech who did not drop the pan for inspection first. Blame Him....
Again, when we do a flush, we drop the pan for inspection, then if all is ok, we pull filter out, hook up the machine to the filter port and truley flush 100% of the old fluid out and replace with clean fluid. After that, we insert new filter, fill trans with fluid and road test. This type of service works very well, cause you check for problems before you flush. We flush vehicles that have over 200,000 miles without problems because of the inspection first....in other words, do it right. The name of the machine we use is TransAction 2.5 and I suggest you look for someone that uses this machine or that at least inspects transmission before flushing. Also, lots of these shops alos tell you that you don't need to change the filter. That is BULL....... You need to change the transmission filter for the same reason you change the engine oil filter. Hope this helps........ more info at websites
Transmission repair in Colorado Springs and Fort Collins and
Automatic Transmission Flush Machine By CTS Inc.