My transmission man told me that the transmission flush machines were the best thing that ever happened to his shop. He won't even let a salesman that sells them in his shop. He sees flushed transmissions daily that have valve body problems. He does flush the coolers, but never the transmisssion.
We have a lot of people coming in our shop with "electrical" problems which are not electric, but valve body problems. In a lot of cases when we say has the transmission been serviced lately they may say, "Yes, I had it flushed at ??? last week". We send them directly to my transmission man. I'm not saying it will happen every time but is happens enough times to make it a problem. Drain all the fluid you can, change the filter, refill and drive it. This is what the transmissions were designed to have done.
My $.00 worth.
Paul

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84 500 SEL (307,xxx miles)