Originally Posted By: JohnBrowning
As long as the shop drops the pan and changes the filter after they flush and they use the proper fluid flushing does not hurt anything! The problem is most shops do not drop the pan they just flush and if the vehicle has a filter that is user serviceable and you do not change it all the clean fluid in the world will not do you any good if the filter is pluged up.
If the shop use's some generic fluid and then uses an additive to make it compatible that is bad too. I called around and in my area their is one transmission shop that drops the pan after they flush a transmission. They also had no problem with me bringing in my own fluid for them to use.
Even the flush chemicals and seal conditioners used are not going to cause any harm in a transmission that is not already damaged. I once tried to kill a tranmission by adding additives to it and as long as I drained out the fluid and refilled with the right stuff nothing I put in including the wrong fluid could kill this transmission. I even went so far as to add MMO until the transmission was slipping like mad and as long as I headed home drained out the fluid and added fresh all was fine! Now to be fair their was nothing wrong with the transimission I was playing around with it had alot of miles on it but had always been maintained by me. The vechile was inmy family from 1991 to 2004. My Dad but the wrong fluid in it and it was driven for about 3 days before the person driving it told me that it was shifting funny and I then changed out what would come out with the drain plug and refilled with the right fluid!Again it fixed it right up. SO people that talk all kinds of B.S. about this or that killing a transmission are full of it. generally you can deviate a heck of a lot until the transmissions starts to malfunction. Once it does start to malfunction though it is super important not to continue to operate it like that if you do it will kill it. The problem is people neglect and abuse their transmissions tot he point that they are almost dead and they do not even know it. Then they get it serviced either becasue they know it needs it or they are hoping it will improve the declining shift quality. then when it fails they always try to blame the flush or the additive etc...... Most people do not put additives into a transmission until they start to act up I have not run into many people that do it just for the heck of it!In top of that most OEM's today recommend idiotic 100,000 mile or life time fill for their automatics almost guaranteeing that they will fail around that time or shortly after.
Then you have the guys that take their car to the drag strip every weekend power break the snot out of their Camaro shift it manual and have done valve body work to it but when the transmission fails then it is the Mobil-1 ATF's fault!
So change the fluid more freq. if it is a small sump and only 3-4 quarts comes out when you pull the plug do it every 16K miles. If you have to drop the pan and you get 8 or more quarts out do it every 30K-50K miles. If you have let it go have your dealership drop the pan change the filter and refill if it has a user serviceable filter. If not then just get it flushed but make sure to use OEM fluids or a fluid that clearly states it is a good fluid for the application you intend to use it in.
No one would go 60K miles and not change their oil and oil filter or just flush it and leave the OEM oil filter on it? A transmission should be treated like the engine with regard to fluid and filter changes. Most people neglect their transmissions, differentials and transfer case's!
If I had an automatic that needed flushing I would add some Auto-RX to it per the instruction and I would drive it at least 2000 miles then I would go get it flushed,pan droped and filter changed if I was not going to do it myself!
I would think dropping the pan, changing the filter, then refilling the pan, then immediately doing a flush would be best as you have almost no mixing of old and new ATF and would require the least new ATF. I too would be cautious of a place that used an ATF+additive to make ATF compatible for my vehicle. Now if they used a multi vehicle ATF like Amsoil or M1 that covered my vehicle thats a different story. Also keep in mind if you bring in your own ATF, you need to ask firmly that they purge the new fluid container of ATF as in many flush machines there is a QT or two of new fluid left after a flush.
