As I have no idea when the last time the fluid was changed in my discovery, I wanted to drain, change the filter, and add new fluid. At 70,000 miles, I am assuming all is original.
Transmission holds 10 quarts from dry.. any ideas how much it will take once I drop the pan, put a new filter in, and button it back up? I have never owned or serviced an automatic before, so this is new to me
Generally there is a drain spec, I'd guess 2 gallons will be enough to get the job done.
3-4 liters is a fairly normal number for a drain and fill.
What's the vehicle (year, make, model)? I work for a transmission manufacturer; I'd be surprised if it really needs to be changed, but it probably wouldn't hurt anything. Don't be worried if theres some metal in the fluid, but if it has magnets in the oil pan you can get to, I'd clean and/or replace them while you're at it. On our models, the drain plug is usually magnetized.
2003 Landrover Discovery. I actually want to drain it twice.. once with some decent fluid before I haul my boat down from NY.. and then again with some redline. I hope that should get all gunk out of it
DON'T DO IT!!! 
Half joking. Auto or manual, I top them off if they need it, or fix them if they're leaking. YMMV.
I can honestly say I've never serviced an automatic. Never had one fail either. Keep them cool, don't let them hunt for a gear, don't make them shift under heavy loads.
Like Poopshovel said, YMMV.
You cant hurt a transmission, auto or manual, by changing the fluid for fresh and cleaning the magnets.
4 quarts should do the job. Plain 'ol Dextron, not the fancy synthetic stuff.
when I had my Suby (AT) I was told by the seller that the AT fluid had been changed out every 30k since new ... when I changed it I was warned to put in exactly as much as I took out ... that it could cause serious damage if overfilled
when I sold it, it had 247k mi. and ran fine
Even if you drop the pan, you still have old stuff in the torque converter and circuits. Drop the pan, do the filter, new gasket. Then, if you disconnect the line where the fluid enters its cooler, with the engine running, you can pump out an even gallon, then add a gallon. Run the shifter through its gates, and keep doing that till the fluid is clear. Just takes two milk jugs, some hose and clamps, and a bunch of the correct fluid.
Hntsvl_E30 is right on the money with how to change it.
As far as the need to change fluid, I'm a big believer that expensive oil/trans fluid is cheaper than a cheap engine/transmission. Since I pull a car trailer with the Trooper, it got a big external cooler and I change the fluid every 30K. I did the filter ~2 years ago (getting to be about that time again come to think of it) and at 175K the pan was as clean as the day it was built. I'm talking ~no~ particles of any kind, other than the normal magnet fuzz.
Hntsvl_E30 wrote: Even if you drop the pan, you still have old stuff in the torque converter and circuits. Drop the pan, do the filter, new gasket. Then, if you disconnect the line where the fluid enters its cooler, with the engine running, you can pump out an even gallon, then add a gallon. Run the shifter through its gates, and keep doing that till the fluid is clear. Just takes two milk jugs, some hose and clamps, and a bunch of the correct fluid.
so.. how do I keep from emptying the entire trans and ruining it?
I've heard a number of differing opinions about this. Some say if the fluid has never been changed, don't eff with it. I have to admit my limited experience with automatics would agree with this. However, if the trans has had regular fluid changes, then its probably not a bad idea.
The flushing procedure for the Volvo 850 is similar to what was described. Do you have a service manual? It's likely in there.
The most important thing is the filter. They tend to get plugged up and restrict fluid flow/pressure.
if you do a full flush, pump out a given amount, say 1qt. shut down and add 1qt fresh fluid, repeat until you have replaced the total capacity.
For a comparison of the two different changes, full to a service fill ( fluid and filter)
Full 28 pts., service 10 pts. this of course will vary.
The procedure I have always used is:
Get the trans nice and warm, then shut the vehicle off and drain it.
Remove pan and filter. Clean pan thoroughly.
Install new filter and reinstall pan.
Fill transmission.
With car on jack stands and foot on the brake pedal, manually run the car through the gears a few times. This will get some of that fresh fluid into the torque converter.
Check fluid level again (it will need more) and top off.
Since this method only replaces ~50% of the fluid every time, if the fluid has NEVER been changed, drive ~5000mi and repeat the whole process. If it HAS been regularly changed, you are good to go.
My dad's E39 is well north of 200k on the original slush box using this method, and he drives it harder than most. It had 150k when we got it and thanks to BMW's "lifetime fill" it had never been changed. There was a discernible difference after the first change, no doubt. Before the change it felt like the torque converter was lightly dragging at freeway speeds, and shifts were sloppy. Now it's smooth as glass with quick, precise shifts.
If your auto trans fluid has more than 100k on it your trans is a time bomb. "Leaving it alone" is NOT the solution. The average shop will try to sell you a pressurized flush that will do more harm than good, and many seem to think that means not to touch it. Wrong! A gentle drain and fill like I describe is the safe way to get a high mile trans working right again.
In reply to SlickDizzy:
The problem is I've done EXACTLY what you've described and have had 100% failure rate shortly afterwards. The trans worked fine before.
Ian F wrote: In reply to SlickDizzy: The problem is I've done EXACTLY what you've described and have had 100% failure rate shortly afterwards. The trans worked fine before.
Out of curiosity, what vehicles were these and what kind of mileage did they have? My success with this method includes a '98 Ram with the 5.7 (64k), '99 528i (150k), '91 XJ6 (110k or thereabouts) and 2001 Taurus (160k or thereabouts). My failure rate is 0% so far. This is the method the BMW guys swear by, which is why I did it to the "lifetime fill" 528 despite my intimidation...and it seems to have worked. I did use OE fluid each time, I didn't want to mess with synthetics and stuff that hasn't already been in there.
I'm not trying to call BS on you but depending on your circumstances maybe a line can be drawn somewhere as far as how late is "too late" to mess with the OE fluid.
'90 E150 w/ AOD ~ 100K miles
'73 1800ES BW35 - 200K miles. "Gee... the fluid has 200K miles on it... maybe we should change it..." ...afterwards: "Why the berk did we do that???? Now it shifts like CRAP!"
'96 Volvo 850 - 130K miles Although in this case we did the fluid change/flush as part of a number of attempts to get the trans to shift correctly and not go into limp mode, so I don't really blame the fluid change. Eventually, after wasting a LOT of money, we gave up and a shop replaced the entire transmission to the tune of ~$4K (not much less than she paid for the entire car). AFAIK, the car has been fine since (we aren't together anymore and I firmly believe her buying that POS car and when I wasn't able to fix every god damn thing that went wrong with it, she decided I was past my "sell-by" date...).
Automatics are made of voodoo and space dust. I generally junk the car if I have an ATX that needs servicing.
well, with my auto just over 70,000 I think I am still short of the "varnish is holding it together stage" I will do a filter and pan drop as said above.. go get my boat, and then do it again afterwards.
Ian F wrote: I've heard a number of differing opinions about this. Some say if the fluid has never been changed, don't eff with it. I have to admit my limited experience with automatics would agree with this. However, if the trans has had regular fluid changes, then its probably not a bad idea. The flushing procedure for the Volvo 850 is similar to what was described. Do you have a service manual? It's likely in there.
it's my understanding that this has to do with the so called power flushes ... just draining and refilling doesn't seem to cause any problems .... or so I've been told 
edit: SlickDizzy beat me to it ... with more than just hearsay to back it up
The other service method I like for auto is:
Unbolt auto trans, throw in junk pile. Bolt in manual trans and 
Gearheadotaku wrote: The other service method I like for auto is: Unbolt auto trans, throw in junk pile. Bolt in manual trans and
The Saturn service method is pretty good too: Remove drain plug, reinstall. Spin off filter, spin on new one. Fill with new fluid.
mad_machine wrote: so.. how do I keep from emptying the entire trans and ruining it?
It's a non issue. The pump finally runs out of fluid to move. That's all. Just turn it off and add more fluid. To damage the pump you'd have to run it several minutes at least.
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