Many of you are wondering how to do a transmission flush without hurting the trans. Most machines at garages are pressurized and use a cleaning agent to flush the system debris out. This is very bad and breaks free hardened deposits in large chunks that can block very small orifices. Since transmission fluid itself is a cleaning agent, installing fresh fluid will clean the inside's itself..over a very long time and is very safe. Now, there are some that allow the transmission to pump the fluid out itself and use no cleaning agents at all, which is what you really want. Speak with the Service writer or technician and ask if they can not use cleaning agents. No cleaning agents unless they'll warranty your trans for damage occurred from the flush!

This is a little explanation on how to do a Transmission flush on your own in your driveway the safe way. It takes about an hour for just fresh fluid and about 2hours for a pan frop and filter change.

System contains 17qts of fluid. Plan on Buying 20qts and using 19 if not 20qts. You can't expect to get all old fluid out if you just use 17qts. Not gonna work. Dont be cheap and spend the extra $25 on 3 more qts and do it right.

Procedure:
1) Lay down a large piece of cardboard under the truck. Overlap pieces if you must. The carboard will absorb any splashes or sprays that may occur and makes clean-up a breeze!
2) Unhook the return line of the transmission. This is the one at the bottom of the trans closest to the pan. I've included a pic below to show you.
3) Once the return line is disconnected, you'll want to place a rubber hose(probably 3/8" inside diameter over the flare fitting. You'll put the other end of the rubber hose into a bucket.
4) Start the truck up and let it idle until the fluid starts to spit/sputter for a few seconds. Then turn the truck off. Now, your trans pan is almost empty and the only remaining fluid left is what couldn't be sucked up through your filter.
5) Now is when you remove your pan and do your filter change. The pan will probably have a little less than 1qt of fluid in it so be careful when removing it. It beats having 7qts dumped on you without following this procedure!!
6) When you get the filter chane and pan all wiped out and all buttoned back up, your going to pour in 7qts of fresh ATF+4. Don't even worry about the dipstick, just leave it out.
7) You'll start your truck again and this time put in gear for only 5sec then go back in park. Let it run until the fluid spits/sputters. Then turn it off.
8) At this point, you pushed out and emptied ~7qts before filter change. You've just pushed out another 6qts with the new fresh fluid(remember there is still ~1qt remaining in pan that filter cannot suck up). That leaves ~4qts of old fluid left plus maybe another 1 or 2qts of flui that has mixed during the process.
9) Pour in 6qts of ATF+4 and run until fluid sputters again.
10) re-install your return line and clean up your mess.
11) Pour in 5qts of fluid and let truck fully warm up. Top off as needed. You'll probably need another 1qt, but it's better to underfill than overfill at this point, granted your not jumping in and driving it around while it's low. It wont hurt anything to be low and idling. Otherwise, you'll have to pop off your retrun line and drain some.

That's it. Your done!
This procedure using the transmission pump to regulate the fluid through the transmission and only flows clean fluid through your new filter. I'd reccomend doing this at 50kmi(fluid flush only) and again at 100kmi(fluid and filter change)
I've done this MANY times and never had any problems. I recently did it on a 120kmi Buick that shifted sloppy and then was super smooth afterwards. Did it again on my new beater with 60kmi with same results! Shifts fantastic afterwards. If there's any sludge or what not inside that the fresh fluid breaks down, the new filter has plenty of capacity to remove it.
If you go through this procedure and have ANY problems shifting or going into gear etc. Pour in a full can of Seafoam and drive it for a few hundred miles or idle for a few hours(and go through the gears) if not able to be driven and then do the whole flush procedure again with fresh fluid. Again, never have I had this problem, but a friend had this done at a garage who used a machine. I told him what to do and afterwards he had a perfect shifting and running transmission. DO NOT use any additives UNLESS you have problems. Also, additives are a patch..meaning temporary solution...not a permanent fix!
Don't be scared, just do it. There's no good reason to let your fluid remain in your transmission because your scared and dont want to do preventative maintenance. The WORSE thing for your trans is old dirty fluid. That WILL cause you problems. Bad and dirty trans fluid cannot dissipate heat. You will fry your clutch packs and break metal components from the excessive heat. FLUSH! I mean...EXCHANGE your fluid. That's all your doing, is an exchange.
ALOT of stories you hear are hearsay from guys who don't know all the specifics or understand how things work when flushing.

**PLEASE NOTE** This is a guide and I will not be held responsible for anything that may happen. Please use responsibly.


545rfe trans pic above
#4 is the return line