Whole Trans fluid change

[Monkeyporn]

OK friends I need to know how to drain my whole transmission including the torque converter. I want to do a whole fluid / filter change. Thanks 'in advance.

 

[07 Boss]

There is always going to be some old fluid left behind but the only way to insure maximum extraction is to hook a machine to it. You can drain and fill it a couple of times also but it will never get everything out unless you pull the tranny and torque converter.

 

[Monkeyporn]

There is always going to be some old fluid left behind but the only way to insure maximum extraction is to hook a machine to it. You can drain and fill it a couple of times also but it will never get everything out unless you pull the tranny and torque converter.

Thanks for replying so by machine do you mean some type of suction machine ? Is that the same machine they do there trans flush with ? I was told not to EVER do a trans flush on these cars as it messing up the solenoids.

 

[07 Boss]

Thanks for replying so by machine do you mean some type of suction machine ? Is that the same machine they do there trans flush with ? I was told not to EVER do a trans flush on these cars as it messing up the solenoids.

Yes, one of those flush machines. As far as doing it or not and messing up solenoids here is my opinion. Yes I have seen trannies not work so well after a flush but that is not because the flushing messed it up but just brings any issues to the surface. If your tranny acts up after a flush it's because there was already a problem but it wasn't evident until afterwards when everything gets un-gunked. If your tranny is currently in good order then a flush won't hurt it. This is just my opinion as well as a few other mechanic friends. But yea I have other friends that say never to do it. Personally I have only done it twice to any of my cars. Even in the Mustang I just drain and fill with a filter change. I've only done it once as I have been through 3 transmissions and have only done drained and filled the current one.

 

[bambam 06]

Here is how i do it, it changes 95% of the fluid. Also i have an external transmission filter which makes it a lot easier. Disconnect the lower hose between the transmission and cooler, run the engine in Park (you need a bucket to collect the fluid) and let the fluid run out. Put 5 or 6 qts of fluid in the trans and do it 2 or 3 times till the fluid looks like new, put the hose back, replace fluid and check to make sure is full. I have a transmission dipstick and tube, so i can refill and check oil with no problems. Without a dipstick tube, then you have to follow Ford guidelines.

 

[JC SSP]

Having a dipstick and filler tube makes it much easier. Still not sure why Ford sealed the transmission on the S197 Mustangs?

 

[Juice]

The converter may have a drain. But Ford phased them out at some point. Pull the rubber plug on the bottom of the bellhousing, and slowly turn engine. If the plug is not there, than your stuck with the "flusher" machine. Drilling and plugging was the norm 40 years ago... lol

 

[Monkeyporn]

Well my cars transmission has never been drained not while I've had it. Car had 110K on it when I got it now has 140K So I guess it's time to address it. It runs fine so I"m guessing from what I'm reading that a flush will be "ok" my only concern is how do I make sure the shop ONLY using genuine ford Mercon V fluid and filter ? I have no issue buying the materials needed but unless I stand there and watch them I have no way of knowing if they use what I gave them. UGH I wish I just had a lift somewhere I could use I just do it myself.

 

[JC SSP]

If you never changed the tranny fluid or cannot confirm it has been done previously, you just might be better off leaving it alone at that mileage level.

Be forewarned, There is a possibility of tranny slipping, clunking, lack of gear engagement etc. if you drain all the old fluid which has a lot of friction material and particles with fresh new clean fluid.

 

[pass1over]

Good advice.
It can be a bad idea to change the fluid in an automatic that's never been changed before.

 

[Laga]

Having a dipstick and filler tube makes it much easier. Still not sure why Ford sealed the transmission on the S197 Mustangs?

Manufacturers started making sealed transmissions for two reasons. The first and least important reason was that the dipstick tube allowed water and dirt into the unit which caused damage. The second and most important reason is that the general public would put in the wrong ATF or motor oil, or windshield wiper fluid. Before he passed from cancer, my buddy was a certified transmission tech for a Cadillac dealer. The vast majority of failed units he worked on was from the wrong stuff being put into the trans, and then people bring them in for a warranty claim. You would have to assume it was the same at other dealers. GM had been working on making a seal trans for years. Synthetic fluids and the fact that ATF is not exposed to combustion gasses allows for extended service intervals and closed units.

 

[86GT351]

The proper way is to have it flushed. Does the transmission, convertor and cooler.

 

[Autokyrios]

Never back-flush an auto. Just don't. It's not a radiator. You'll do your transmission more good by licking it than back-flushing it. (Actually don't do that either...the 5R55S tastes bad.)

Ford and transmission shops have transmission flushing machines that basically pump in new fluid while draining out the old, by connecting to the cooler lines. I'm on the fence about shops that service other types of cars doing this because not all transmissions use the same fluid and processes so best to go to Ford or a shop that knows how to work on Ford-used transmissions.

Only way to get 100% of the fluid out is taking the transmission/TC out of the vehicle. That's not what you probably actually want, though.

There's no factory dipstick or from-top fill tube (5R55S is not exactly the same as the N from the explorer, either).

If you crawl under and look at the pan, you'll see a two-part (very important) drain plug. Should say right on it something like "outer for drain, inner for fluid check" or similar. There is no easy process for going back if you drain the transmission, so if you want to do that, read on for all the fun steps. Otherwise, just leave it alone.

IF you want to tackle this yourself, you need a few things:
1. Fluid, duh (ask if you need info on this)
2. Filter (this is a good kit: https://lmr.com/item/LRS-5R55SVC/mustang-5r55s-transmission-service-kit-05-10)
3. Pump (with clear tubing) to push fluid UP into the transmission (make sure it's easy to use)
4. Either the correct fill fitting for a 5R55S, or a 1/8NPT to barb fitting (can source from any hardware store) I recommend the correct fitting but I do keep a couple of the brass ones around as backups because you're kinda screwed if you don't have anything
5. A safe secure way of running the car (AND being able to put it into each gear) while it's up in the air and you're crawling under it (you only need to do so when it's in P or N...no spinning driveshaft fun here).
6. Some way of telling when the transmission is up to temperature (a tuning device that can show real-time data logging or something to read from the ODBII...I doubt you have a trans temp gauge installed...ask if you'd like to)
7. Self loathing (you will...but don't worry it mostly goes away after you do this a few times)

Draining:
Draining is as easy as draining engine oil, only difference is you want to do it after its been sitting off for a while, as when the auto is churning it sucks up an amount of oil that drains back at rest. If you do it hot, you'll either sit there forever waiting for it to drain, or it just won't fully drain (what it would fully drain this way that is). Just get a pan good enough for about 8qts and undo the big plug. You'll get about 70% out.

There's usually some fluid in the transmission cooler as well, but it's negligible and not the easiest to get to (sandwiched between the condenser and radiator with AC bits in the way). Wouldn't worry about it.

Don't run the car without fluid in the trans. It won't get you any qualitative fluid and you risk damaging things.

Before Filling:
IF this is your first time getting into the 5R55S and you're doing the job yourself, do yourself a favor and drop the pan. It's a dozen or so 8mm bolts and then it just drops down. There's a reusable gasket (assuming it's original) but after 100k miles it's worthless IMO. Either get a new one from Ford, though I recommend the one from Lube-Locker. You do not need to use any gasket sealer or whatever (if your pan gasket is leaking, you did something wrong or the gasket is bad).

Once you drop the pan, there's a magnetic donut in there. Have a look for any metal bits (heavy glitter) and clutch material (rust-like sediment). Ideally there shouldn't be any, but with a "sealed" transmission and no temp gauge, these things are Schrodinger boxes that most people don't understand how often they actually cook. If you're unsure of the results, post picks. If you find anything that looks like a physical object (strip of metal, piece of screen, metal chunks or bolt bits) congratulations, a new 5R55S is in your future! (Been there, it was actually fun.)

Next exam the filter (rectangle-ish flat thing bolted to the underbelly guts of the transmission...looks like the new one you should have waiting nearby). Undo the bolts and then wiggle it out (there's an ingest tube sticking up into the transmission that's part of the filter that has a gasket on it, and with age or heat they can get stuck...if it doesn't wiggle, something's still bolted). Don't tip it over, save it as is like an oil filter for examination. Chances are, if you didn't find anything in the pan, the filter won't have anything to say either. You can pry it open or cut it open if you want, otherwise reward it for its service by chucking it into a bin.

Note: The 5R55S has a short pickup tube for the Mustang's pan. If you incorrectly got a 5R55N filter, it will have a long pickup tube. The good news is you can trim it, just make sure it exactly matches the length of the original filter pickup, or you'll have problems. Best to just make sure you have the right one to begin with.

Attach the new filter same as the old by first pushing the gasket-equipped tube up into the transmission until the filter seats against the transmission, then bolt. DO NOT over tighten the bolts, you'll crack the filter and/or damage the transmission...it's delicate...treat it nice.

Clean up the pan real good, then re-attach it (don't forget the gasket). I don't have the bolt torque specs on me but will update the post later with the pattern and spec.

Filling:
Now the fun part.

(I'm assuming the car is level...if not, you need to make it level.)

Take the inside part of the drain plug out. Screw the outer part back into the pan snuggly (should have a gasket) as you shouldn't need to take this out again until your next refill.

Gently (so you don't cross thread) screw in the fill attachment (either the refill tool or your bass fitting) in where the center part of the drain plug was. Connect up your tubing and pump and fill up the pan about 3qts and STOP. Don't listen to the spec on how many qts the transmission uses. Remember that some fluid is still up in there, and there's a process to go through.

Take the tubing off the filler and get a pan ready.

What you want to do first is pump in just enough fluid so that NONE drains back out of the inner hole when you disconnect the tube, BUT you want to get to that point first (where fluid is coming out). This means the fluid level is currently at the level of the plug's raised inner section (you probably saw how the drain plug had a bit of a metal tube riser on the inside...it's there to gauge the fluid depth). If fluid is over that height it'll drain out, if under, it won't drain...it's a game and no two situations will be the same. Enjoy.

Okay, once you have that established, reconnect your pump tubing and crawl out from under the car.

Start the engine (keep the car in park). Let it sit until the car is up to normal temperature (coolant gauge is up at normal).

If you don't have a way to read the temperature of the transmission, you can still do this but it's a guess. Don't worry, you'll be fine, it just means potential adjustments to the fluid level later on).

Either check that the transmission temperature is at normal operating range, or you think it is. You'll need to put the transmission into drive and let it spin for a bit. Keep your foot near your brake and don't give it any gas. You want the transmission to do turning, that's all. Honestly feathering the brake to just do slow 2-5mph rotations is fine. (I'll hunt down the normal temp and add it but it's not cooking so no need to spin things up hard.)

Now cycle through the gears up and down at least once, using your brake in between of course and letting it spin a bit in each gear (don't worry about the overdrive switch). Basically to run each gear the transmission has to suck up fluid and do it's witchcraft, so if you want a better fluid level reading you need to let it do its thing.

Now put it back in Park and go back under the car (careful of hot stuff....car stuff not...eh, you get it).

See if any fluid is draining out. Shouldn't be. You should actually be a little low at this point. Pump some fluid in until it drains back out (like 1/4 to 1/2 a qt but it's not an exact thing).

Once you've re-established a level fluid reading (fluid goes in, drains out and then stops) go back up into the cockpit and work the transmission again, cycling through the gears and all.

Rinse, repeat.

The trick is to make sure the transmission is in its temperature band when doing this, otherwise it'll have either low or high levels in the pan.

Here's a tick if you don't have a way to read the temp: err on the side of caution and do the cycling at real slow speeds, and assume you're gonna be a little low on your fill job.

Once you've done this dance about 3-4 times (after about 2 you're probably not seeing a change anymore, which means things are good) take your tubing out, take the INSIDE fitting out, and put the stock inside plug back in place. No tape or anything required, just gently snug and it'll be fine.

Now, go for a very short test drive (like, your driveway short). Backing out the car, drive it forward a little in D, then in each gear, then reverse, then let it sit. Then go for an actual casual drive (actual casual not Rat Fink casual).

The transmission MAY slip up a little a couple times at first, but then it should be okay, especially under harder throttle. If it's slipping a bunch (or you just feel odd about it) bring it back, put it back up one stands or whatever, and check the fluid level (car on and warm, inside plug out, see if fluid drains, if not add some till it comes out then stops). Without a dipstick tube this part's a pain in the backside.

What happens if you over fill the transmission? Well, two things.
1. It's a pressurized hydraulic system, so when there's too much fluid, it has to go somewhere. There IS an expansion drain (wonderfully located on top of the transmission where you can't reach it) and it'll spit fluid out there if you're really high. Only way you'll probably know is by crawling under the car and finding your transmission covered in fluid like it's been peed on by the oil fairies, since it likely won't pressurize enough to vent this out just sitting where its parked.
2. Your transmission will overheat. Sounds dumb (maybe it is) but what happens with a too-full transmission is the oil will start to foam up and trap heat and cause problems in the fluid chain.

What happens if you did all this and the transmission is still slipping like crazy?
Well, either your filling setup isn't actually level so you're getting a bad reading, you're using the wrong fluid, or chances are something's actually wrong with the transmission. I would take it to a good shop that does transmissions, or of course to Ford and let them diagnose. This post would be much longer if I listed all the other things that these special magical *itch boxes can come up with.

Oh, and in case you're wondering, yes, I have added a dipstick/fill-tube to my car because f**k life without it! I also have a built transmission/TC.

I'll find those specs in an hour or so.

 

[86GT351]

SO you are saying the Flush machine we have here at Ford does not work?

 

[Autokyrios]

Sorry, explorers have a 5R55W as well. I think the N is for 2WD and W is for the 4WD but I can't recall.
Transmission operating temp: 80-120F
Fitting from Ford is ST2581-A but I only have one from Ford and the others I have are from other companies.
Mercon V fluid. I've used Royal Purple but have had the best results with Motorcraft. (don't put IV in it)
8 ft-lbs for the pan bolts
10 INCH pounds for the filter bolts.

 

[Autokyrios]

SO you are saying the Flush machine we have here at Ford does not work?

Don't BACK-flush. Flush = forward, back-flush = reverse. Never a good idea to send crap back through a transmission. (Yeah, the Ford machine is a system flusher...I'm more warning about shops that just backflush willy-nilly. I'd trust the Ford system for what its purpose is...flushing fluid).
You can back-flush the cooler, though. It's just a plain tube with no intricate passages.

Frankly I wouldn't do either direction in a transmission without checking the pan first. If there's bits in the pan, flushing the transmission ain't gonna solve the problem.

Ford does say if there's any suspected or detected damage you gotta clean it all out. Though results of flushing a clean transmission outside of refreshing fluid is up for debate. IMO it does no good (outside of changing the fluid).

(Didn't mean to say that changing the fluid is bad...I don't believe the fluid is good for the 100k miles Ford claims, so if everything is fine, go for it. I'd still check the pan, though.)

 

[Monkeyporn]

Never back-flush an auto. Just don't. It's not a radiator. You'll do your transmission more good by licking it than back-flushing it. (Actually don't do that either...the 5R55S tastes bad.)

Ford and transmission shops have transmission flushing machines that basically pump in new fluid while draining out the old, by connecting to the cooler lines. I'm on the fence about shops that service other types of cars doing this because not all transmissions use the same fluid and processes so best to go to Ford or a shop that knows how to work on Ford-used transmissions.

Only way to get 100% of the fluid out is taking the transmission/TC out of the vehicle. That's not what you probably actually want, though.

There's no factory dipstick or from-top fill tube (5R55S is not exactly the same as the N from the explorer, either).

If you crawl under and look at the pan, you'll see a two-part (very important) drain plug. Should say right on it something like "outer for drain, inner for fluid check" or similar. There is no easy process for going back if you drain the transmission, so if you want to do that, read on for all the fun steps. Otherwise, just leave it alone.

IF you want to tackle this yourself, you need a few things:
1. Fluid, duh (ask if you need info on this)
2. Filter (this is a good kit: https://lmr.com/item/LRS-5R55SVC/mustang-5r55s-transmission-service-kit-05-10)
3. Pump (with clear tubing) to push fluid UP into the transmission (make sure it's easy to use)
4. Either the correct fill fitting for a 5R55S, or a 1/8NPT to barb fitting (can source from any hardware store) I recommend the correct fitting but I do keep a couple of the brass ones around as backups because you're kinda screwed if you don't have anything
5. A safe secure way of running the car (AND being able to put it into each gear) while it's up in the air and you're crawling under it (you only need to do so when it's in P or N...no spinning driveshaft fun here).
6. Some way of telling when the transmission is up to temperature (a tuning device that can show real-time data logging or something to read from the ODBII...I doubt you have a trans temp gauge installed...ask if you'd like to)
7. Self loathing (you will...but don't worry it mostly goes away after you do this a few times)

Draining:
Draining is as easy as draining engine oil, only difference is you want to do it after its been sitting off for a while, as when the auto is churning it sucks up an amount of oil that drains back at rest. If you do it hot, you'll either sit there forever waiting for it to drain, or it just won't fully drain (what it would fully drain this way that is). Just get a pan good enough for about 8qts and undo the big plug. You'll get about 70% out.

There's usually some fluid in the transmission cooler as well, but it's negligible and not the easiest to get to (sandwiched between the condenser and radiator with AC bits in the way). Wouldn't worry about it.

Don't run the car without fluid in the trans. It won't get you any qualitative fluid and you risk damaging things.

Before Filling:
IF this is your first time getting into the 5R55S and you're doing the job yourself, do yourself a favor and drop the pan. It's a dozen or so 8mm bolts and then it just drops down. There's a reusable gasket (assuming it's original) but after 100k miles it's worthless IMO. Either get a new one from Ford, though I recommend the one from Lube-Locker. You do not need to use any gasket sealer or whatever (if your pan gasket is leaking, you did something wrong or the gasket is bad).

Once you drop the pan, there's a magnetic donut in there. Have a look for any metal bits (heavy glitter) and clutch material (rust-like sediment). Ideally there shouldn't be any, but with a "sealed" transmission and no temp gauge, these things are Schrodinger boxes that most people don't understand how often they actually cook. If you're unsure of the results, post picks. If you find anything that looks like a physical object (strip of metal, piece of screen, metal chunks or bolt bits) congratulations, a new 5R55S is in your future! (Been there, it was actually fun.)

Next exam the filter (rectangle-ish flat thing bolted to the underbelly guts of the transmission...looks like the new one you should have waiting nearby). Undo the bolts and then wiggle it out (there's an ingest tube sticking up into the transmission that's part of the filter that has a gasket on it, and with age or heat they can get stuck...if it doesn't wiggle, something's still bolted). Don't tip it over, save it as is like an oil filter for examination. Chances are, if you didn't find anything in the pan, the filter won't have anything to say either. You can pry it open or cut it open if you want, otherwise reward it for its service by chucking it into a bin.

Note: The 5R55S has a short pickup tube for the Mustang's pan. If you incorrectly got a 5R55N filter, it will have a long pickup tube. The good news is you can trim it, just make sure it exactly matches the length of the original filter pickup, or you'll have problems. Best to just make sure you have the right one to begin with.

Attach the new filter same as the old by first pushing the gasket-equipped tube up into the transmission until the filter seats against the transmission, then bolt. DO NOT over tighten the bolts, you'll crack the filter and/or damage the transmission...it's delicate...treat it nice.

Clean up the pan real good, then re-attach it (don't forget the gasket). I don't have the bolt torque specs on me but will update the post later with the pattern and spec.

Filling:
Now the fun part.

(I'm assuming the car is level...if not, you need to make it level.)

Take the inside part of the drain plug out. Screw the outer part back into the pan snuggly (should have a gasket) as you shouldn't need to take this out again until your next refill.

Gently (so you don't cross thread) screw in the fill attachment (either the refill tool or your bass fitting) in where the center part of the drain plug was. Connect up your tubing and pump and fill up the pan about 3qts and STOP. Don't listen to the spec on how many qts the transmission uses. Remember that some fluid is still up in there, and there's a process to go through.

Take the tubing off the filler and get a pan ready.

What you want to do first is pump in just enough fluid so that NONE drains back out of the inner hole when you disconnect the tube, BUT you want to get to that point first (where fluid is coming out). This means the fluid level is currently at the level of the plug's raised inner section (you probably saw how the drain plug had a bit of a metal tube riser on the inside...it's there to gauge the fluid depth). If fluid is over that height it'll drain out, if under, it won't drain...it's a game and no two situations will be the same. Enjoy.

Okay, once you have that established, reconnect your pump tubing and crawl out from under the car.

Start the engine (keep the car in park). Let it sit until the car is up to normal temperature (coolant gauge is up at normal).

If you don't have a way to read the temperature of the transmission, you can still do this but it's a guess. Don't worry, you'll be fine, it just means potential adjustments to the fluid level later on).

Either check that the transmission temperature is at normal operating range, or you think it is. You'll need to put the transmission into drive and let it spin for a bit. Keep your foot near your brake and don't give it any gas. You want the transmission to do turning, that's all. Honestly feathering the brake to just do slow 2-5mph rotations is fine. (I'll hunt down the normal temp and add it but it's not cooking so no need to spin things up hard.)

Now cycle through the gears up and down at least once, using your brake in between of course and letting it spin a bit in each gear (don't worry about the overdrive switch). Basically to run each gear the transmission has to suck up fluid and do it's witchcraft, so if you want a better fluid level reading you need to let it do its thing.

Now put it back in Park and go back under the car (careful of hot stuff....car stuff not...eh, you get it).

See if any fluid is draining out. Shouldn't be. You should actually be a little low at this point. Pump some fluid in until it drains back out (like 1/4 to 1/2 a qt but it's not an exact thing).

Once you've re-established a level fluid reading (fluid goes in, drains out and then stops) go back up into the cockpit and work the transmission again, cycling through the gears and all.

Rinse, repeat.

The trick is to make sure the transmission is in its temperature band when doing this, otherwise it'll have either low or high levels in the pan.

Here's a tick if you don't have a way to read the temp: err on the side of caution and do the cycling at real slow speeds, and assume you're gonna be a little low on your fill job.

Once you've done this dance about 3-4 times (after about 2 you're probably not seeing a change anymore, which means things are good) take your tubing out, take the INSIDE fitting out, and put the stock inside plug back in place. No tape or anything required, just gently snug and it'll be fine.

Now, go for a very short test drive (like, your driveway short). Backing out the car, drive it forward a little in D, then in each gear, then reverse, then let it sit. Then go for an actual casual drive (actual casual not Rat Fink casual).

The transmission MAY slip up a little a couple times at first, but then it should be okay, especially under harder throttle. If it's slipping a bunch (or you just feel odd about it) bring it back, put it back up one stands or whatever, and check the fluid level (car on and warm, inside plug out, see if fluid drains, if not add some till it comes out then stops). Without a dipstick tube this part's a pain in the backside.

What happens if you over fill the transmission? Well, two things.
1. It's a pressurized hydraulic system, so when there's too much fluid, it has to go somewhere. There IS an expansion drain (wonderfully located on top of the transmission where you can't reach it) and it'll spit fluid out there if you're really high. Only way you'll probably know is by crawling under the car and finding your transmission covered in fluid like it's been peed on by the oil fairies, since it likely won't pressurize enough to vent this out just sitting where its parked.
2. Your transmission will overheat. Sounds dumb (maybe it is) but what happens with a too-full transmission is the oil will start to foam up and trap heat and cause problems in the fluid chain.

What happens if you did all this and the transmission is still slipping like crazy?
Well, either your filling setup isn't actually level so you're getting a bad reading, you're using the wrong fluid, or chances are something's actually wrong with the transmission. I would take it to a good shop that does transmissions, or of course to Ford and let them diagnose. This post would be much longer if I listed all the other things that these special magical *itch boxes can come up with.

Oh, and in case you're wondering, yes, I have added a dipstick/fill-tube to my car because f**k life without it! I also have a built transmission/TC.

I'll find those specs in an hour or so.

WOW ! This is the most thorough explanation I've gotten and I'm most thankful for it. Sounds like what I need to do for this job is take the car to a ford dealer and have them drain the fluid completely and replace the filter and fluid with genuine ford Mercon V. I may see if I can find a deep pan with a Dipstick and have them install it at the same time since they have to remove the old pan anyway. Anyone know where I can get one ?

 

[MasterofDisaster]

Yes, one of those flush machines. As far as doing it or not and messing up solenoids here is my opinion. Yes I have seen trannies not work so well after a flush but that is not because the flushing messed it up but just brings any issues to the surface. If your tranny acts up after a flush it's because there was already a problem but it wasn't evident until afterwards when everything gets un-gunked. If your tranny is currently in good order then a flush won't hurt it. This is just my opinion as well as a few other mechanic friends. But yea I have other friends that say never to do it. Personally I have only done it twice to any of my cars. Even in the Mustang I just drain and fill with a filter change. I've only done it once as I have been through 3 transmissions and have only done drained and filled the current one.

AAMCO explained to me 30 years ago that if the ATF get too hot, it will leave varnish all over the inside of the tranny. When you change the fluid and filter, the new fluid strips the varnish, and it plugs up the tiny little valves the tranny needs to work right.