Trans Fluid Change

Delor

Original poster
Member
Jul 11, 2012
12
I hae 121,000 miles on my '04 Envoy XUV. I am going to be adding a tranny cooler in 2 weeks. I assume this is the perfect time to change the trans fluid. I am not sure if this has ever been done or not!:eek: I bought it with 71,000 miles on it and I haven't ever done it, so I know it at least has 50K on the fluid.

What is the best way to do this? I assume I am going to be dropping the pan and changing the filter too, right? What type of fluid should I put back in? I do some light/medium towing periodically (hence why I am adding the cooler). I would really like this vehicle to last a while, as it is perfect for my family.

Any suggestions or tips would be greatly appreciated!
 

Sparky

Member
Dec 4, 2011
12,927
I have used the dex/merc in the red bottle at autozone, advance auto, etc. Red jugs, valvoline I believe. Yes, definitely drop the pan and put a new filter in there. If you do just a pan drop it will only change half the fluid however. If you want to change all of it you can disconnect the one cooler line from the radiator and idle the vehicle to pump it empty into a bucket (shut off the engine as soon as the fluid starts sputtering). There was a write up at the old site how to go about the whole process. I did this when I serviced my transmission (I also installed a transgo kit to increase durability/reliability) and it was great. No horrible mess when dropping the pan either since most of hte fluid was pumped out of it.
 
Dec 4, 2011
520
Sparky is about right you will only get about 1/2 if you just drop the pan. Something else to be aware of is there are two tranny filters for our vehicles, you will need to get the proper one. A vin check at a dealer will tell you whether it is the shallow or deep pan one. Another good idea is to install a drain plug in the pan when you have it off for cleaning and filter replacement. As for fluid I would recommend any synthetic tranny fluid from Amsoil, Royal Purple, Mobil 1 and etc. You will need 12-14 quarts for a full change.
 

Sparky

Member
Dec 4, 2011
12,927
Good mention on the filter, forgot about that. But easier way than looking it up with the VIN is to just look at the transmission pan. If it has a little step in it, then it is the deep pan. If it is completely flat across the whole thing, it is the shallow pan. Odds are you'll have the deep pan but it is always a good idea to double check.
 

Mooseman

Moderator
Dec 4, 2011
25,472
Ottawa, ON
For fluid recommendation, use Dexron VI. GM uses it exclusively regardless of the year and it is synthetic at a lower price. All the other synthetics are based on the old Dexron III specs. Plus, since Dexron III is no longer used or licensed by GM, there is no control over its specs.

And the method described by disconnecting one of the cooler lines works great. It does take more fluid to do but it's worth it if it hasn't been done in a long time.
 

Delor

Original poster
Member
Jul 11, 2012
12
Is there any merit to the school of thought that swapping out all the old fluid might actually do more harm than good by knocking something loose? I want to extend my transmission life, not shorten it.
 
Dec 4, 2011
520
Delor said:
Is there any merit to the school of thought that swapping out all the old fluid might actually do more harm than good by knocking something loose? I want to extend my transmission life, not shorten it.

My opinion only. If changing the fluid results in a tranny failure, it was only a matter of time before it went anyway. How can new fluid with the proper additives cause a failure while a worn out fluid would hold things together. Sorry this does not compute. :twocents:
 

Mooseman

Moderator
Dec 4, 2011
25,472
Ottawa, ON
We've had people here and the OS say that their tranny died after such a flush. I can testify that my my fluid was browner than ****. I did my own flush as explained in the OS article. One year later, still going strong. This is in a truck where I have replaced everything but the tranny.
 

Sparky

Member
Dec 4, 2011
12,927
I think what causes a transmission to fail after fluid change is not the new fluid but because some places do a "backflush" of the transmission. This knocks gunk caught in the filter back off the filter and shoves it backwards into the workings of the transmission and valve body. And of course, most places that do said backflush don't even then pull the pan and filter :no:

Transmission backflushes are the devil. Doing a proper "forward" flushing of replacing all the fluid and then putting a new filter in should never be the cause of a dead transmission.

Perfect example - my brother had a 1995 beater Ford Taurus for a little while. It had something like 140 thousand miles on it or something, I don't recall exactly. Transmission fluid had never been changed and was browner than mud. The transmission started slipping quite a bit. He had it forward flushed out, all new fluid and filter, and wouldn't you know that fixed it. He doesn't have the car anymore but the guy he sold it to still drives it every day and it hasn't missed a beat.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
IIRC, the consensus was, the power/forced flush was what was causing problems in high mileage transmissions. Especially if it was a first time flush.
 

Lima Tango

Member
Dec 4, 2011
242
I just did the full fluid swap by pumping out through through the cooler line in addition to dropping the pan and replacing the filter. There was a fair amount of icky sticky grime in the pan and on the magnet but no metal shavings. I used 14 qts of the Walmart brand(supertech maybe?) of Dexron VI and a Wix filter and it is night and day difference, big improvement in shifting over the 90k mile stock fluid. The fluid was bark brown/burgandy.

At the same time, I installed the PCM4L trans cooler. Their instructions were really poor but the kit was awesome. I took my time on the whole project, probably about 5 hours, but when I filled it up and ran it not a single drip in sight :wootwoot: I spent $179 on the kit and ~$90 on the fluid and filter and am seeing about 30 degrees (F) lower trans temps and greatly improved shifting so I think it was well worth it!
 

Vonhendon

Member
Dec 7, 2011
55
I had my Trans flushed back in 2008 at 125K, not long after that I joined the OS and read that this wasn't a good idea. Fortunately it didn't mess my Tranny up but now I'm at 180K and want to drop the pan and clean it and change the filter. So if I pull the line on the trans cooler on the pass. side to pump the fluid out is this considered a forward flush? A shop wants to charge me $235 to change filter and add 5 or 6 quarts of the DexVI, They don't recommend the flush with this many miles.
 

Mooseman

Moderator
Dec 4, 2011
25,472
Ottawa, ON
The flushes that are not good are the ones in quick lube shops as they use a machine to pressure flush using the lines and don't even drop the pan. On top of that, they probably wouldn't even use DexVI.

What the cooler line disconnect method does is just pump the fluid out and replace it all with fresh fluid using the tranny's own pump to do it in the normal fluid flow. As long as you drop the pan and replace the filter, it's good. Plus it's less messy. The cleanest tranny fluid change I ever did.
 

Lima Tango

Member
Dec 4, 2011
242
deepblue said:
Can someone describe the steps involved in this method ?

Pretty simple, actually.

Get a roll of 1/2" clear plastic tubing and a 5 gallon bucket from the likes of Home Depot.

Look at the bottom of the radiator - there are two 1/2" metal tubes going to either side of the radiator. Those are the transmission fluid tubes that pump fluid through the internal trans cooler.

Uncoil your plastic tubing, running one end into the 5 gallon bucket, taking care to clamp it or otherwise ensure it won't go flying out of the bucket when fluid is pumping through it. Take the other end under the truck near the bottom of the radiator, and put down a tarp or other means of protecting your workspace from inevitable fluid leakage.

On the passenger side tube at the radiator, slide the little black plastic cover back off the nut. There is an E clip that retains the flared tube in the female side - this can be a little weird until you do it once or twice, but it was easiest for me to push it back a little until I could grab it with needle nose pliers and pull it off. Grab your plastic tubing, and pull the metal tube straight back out of the hole. It will start to leak fluid - immediately push your plastic tubing as far as you can onto the end of it to run the fluid from that metal tube into your bucket. Stick a cloth or something into the open hole on the bottom of the radiator to prevent undue mess.

Start the truck - it will begin pumping around 5 quarts of fluid into your bucket. As soon as it starts to pump air instead of fluid, shut down the vehicle.

Now, drop the pan, replace the filter, clean the pan, and reinstall.

If it's not already on the ground, lower the vehicle. Pour 5 quarters of fluid into the dipstick, and let it settle. Prepare several quarts of ATF within easy grasp and with their lids off because you'll need to continually be pouring ATF into the dipstick as it's running.

Start the truck again - it will have quite a bit of air at first then will begin to pump fluid. Keep pouring in the ATF and watching the fluid pump out until it has the cherry red coloring of fresh ATF. Your bucket should be around 75-80% full at this point.

Turn off the truck.

Remove the plastic tubing, slide that E clip back onto the nut, and reinstall the metal pipe into the radiator. You should hear a click when it engages, and make sure it doesn't pull back out. Then slide the plastic cover back on there.

Finally, warm up the transmission and top of the fluid the needed.
 

Ace1875

Member
Mar 29, 2012
276
Lima Tango said:
Pretty simple, actually.

Get a roll of 1/2" clear plastic tubing and a 5 gallon bucket from the likes of Home Depot.

Look at the bottom of the radiator - there are two 1/2" metal tubes going to either side of the radiator. Those are the transmission fluid tubes that pump fluid through the internal trans cooler.

Uncoil your plastic tubing, running one end into the 5 gallon bucket, taking care to clamp it or otherwise ensure it won't go flying out of the bucket when fluid is pumping through it. Take the other end under the truck near the bottom of the radiator, and put down a tarp or other means of protecting your workspace from inevitable fluid leakage........

if you are undoing the line from the radiator the 1/2" tube is TOO small for the threaded end, use any old garden hose. cut it around 4feet and clamp the end on the threaded radiator metal hose and clamp the other end in the bucket.

MAKE SURE U CHECK THE GARDEN HOSE FOR LEAKS BEFORE YOU DO THIS.
 

Lima Tango

Member
Dec 4, 2011
242
Ace1875 said:
if you are undoing the line from the radiator the 1/2" tube is TOO small for the threaded end, use any old garden hose. cut it around 4feet and clamp the end on the threaded radiator metal hose and clamp the other end in the bucket.

MAKE SURE U CHECK THE GARDEN HOSE FOR LEAKS BEFORE YOU DO THIS.

You should NOT be unscrewing the fitting from the radiator, if I am reading you right. If you do it the right way and just pull the E clip off and pull out the tube, the 1/2" tubing works as written.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
The "E" clips on the trans fluid lines, are what hold the line into the trans cooler at the radiator.
They are springy steel wire that resemble the letter "E".
There is, or should be, a black plastic cap covering it.
 

C-ya

Member
Aug 24, 2012
1,098
xj2202009 said:
nice writeup,

What's an e clip?

does any one have pics?

They come in different sizes.

E-Clip | AutoZone.com

Speaking of this, both of my lines are leaking where they go into the radiator. I'll be changing the fluid soon, and will most likely use this method so I can disconnect and clean these fittings. Hopefully that solves my problem.
 

Wooluf1952

Member
Nov 20, 2011
2,663
Milwaukee, Wisconsin
C-ya said:
They come in different sizes.

E-Clip | AutoZone.com

Speaking of this, both of my lines are leaking where they go into the radiator. I'll be changing the fluid soon, and will most likely use this method so I can disconnect and clean these fittings. Hopefully that solves my problem.


The clip for the trans cooler lines, look something like that, but are just round spring steel.
Also, you might need new o-rings to stop the leak.
 

C-ya

Member
Aug 24, 2012
1,098
Wooluf1952 said:
Also, you might need new o-rings to stop the leak.

Thanks! That was my next step as I just downloaded the service manual - look at the diagram and see if there was some kind of replaceable seal/o-ring.
 

jricharc

Member
Oct 18, 2012
3
I am going to change the fluid out this weekend in my wife's 9-7x, I am also installing a Corvette servo. Has anyone ever run Seafoam trans tune through the tranny before changing their fluid?

I have always had good success with Seafoam products in my gas and through my intake before a plug change but I have never done the trans tune.

View attachment 23396
 

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Sparky

Member
Dec 4, 2011
12,927
I'm leery of running any cleaning agents through a transmission like that.
 

WarGawd

Member
Sep 2, 2012
468
jricharc said:
I am going to change the fluid out this weekend in my wife's 9-7x, I am also installing a Corvette servo. Has anyone ever run Seafoam trans tune through the tranny before changing their fluid?

I have always had good success with Seafoam products in my gas and through my intake before a plug change but I have never done the trans tune.

View attachment 9974

I used it on mine for 2 days/~300km prior to a full pan drop/flush/filter. After the first 6 hours / 100 km, I had already noticed a significant darkening of the fluid from lightish brown tinge to quite dark and seemingly thicker almost to the point of seeming like sludge. That was Sat/Sun/Mon - obviously can't say anything about long term effects. FWIW I chose NOT to add any to the new fluid per Seafoams recommendations.

Not sure how much value there is in only showing you a picture of the post seafoam treated fluid, cuz I didn't get a Pre one, but if you want I can post it
 

jricharc

Member
Oct 18, 2012
3
Did you notice a difference is the shifting after running it through the tranny and then doing the fluid/filter change? I don't plan on adding any to the new fluid I was just curious about adding some to the old fluid to run through prior to changing it out to "clean" any build up inside the transmission.

I have half a bottle left over after I got some for an old ford taurus I did a fluid/filter change on that was slipping like crazy so I added it to the new fluid and it helped with the slipping along with the new fluid/filter. I am not having any issues with the tranny and I hope to keep it that way thats why I am doing the fluid/filter change @60k and I had this stuff left over so I thought I would see folks thoughts on using it as a cleaner.
 

WarGawd

Member
Sep 2, 2012
468
jricharc said:
Did you notice a difference is the shifting after running it through the tranny and then doing the fluid/filter change? I don't plan on adding any to the new fluid I was just curious about adding some to the old fluid to run through prior to changing it out to "clean" any build up inside the transmission.

I have half a bottle left over after I got some for an old ford taurus I did a fluid/filter change on that was slipping like crazy so I added it to the new fluid and it helped with the slipping along with the new fluid/filter. I am not having any issues with the tranny and I hope to keep it that way thats why I am doing the fluid/filter change @60k and I had this stuff left over so I thought I would see folks thoughts on using it as a cleaner.

I had no issues with the way mine shifted prior to fluid change. Having only bought it in July with zero knowledge of prior service history, I wanted to do all the service stuff because the mileage was right for it (and for the transfer case, possibly 50k overdue), and let that be my baseline. In the process I discovered former owner installed an external cooler, implying he had been towing with it, and making it even more prudent to change - and the fluid itself was starting to turn brownish although I've read that that alone is not necessarily an indication of contamination/oxidation.

So I never saw any difference, I just sleep better ;-)

My use of Seafoam was exactly as your intended use - pre-service cleaning. IMHO 1/2 can is not the correct amount - 1/2 can is for 'An “average fluid capacity” automatic transmission..', so I just used the whole can based in part on past experience using it for the engine prior to oil change (FYI reading the MSDS for Trans Tune and Seafoam's regular Motor Treatment, I am 95% sure they are identical, with the original being re-packaged & re-purposed for transmission use), and knowing I would be doing a full flush within a day or 2.
 

jricharc

Member
Oct 18, 2012
3
Thanks for the info! I appreciate all of the feedback, will just run the half a can I have through it beginning today and change the fluid/filter out Sunday.
 

KrisE

Member
Sep 19, 2013
33
Sparky said:
Good mention on the filter, forgot about that. But easier way than looking it up with the VIN is to just look at the transmission pan. If it has a little step in it, then it is the deep pan. If it is completely flat across the whole thing, it is the shallow pan. Odds are you'll have the deep pan but it is always a good idea to double check.

Just throwing this in here for the Saab 9-7x. I called the Saab Dealership with my VIN and the filter part number for mine at least is # 24208576 I also got 10% off Transmission and Transfer Case Fluids at Napa with my AAA card.
 

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