The dreaded Transmission Flush

[pgibbzz]

Yes, you heard it, the LAST thing on my list of many repairs that hopefully get me to 160K. I plan on doing the COMPLETE flush, drop pan and filter. I cant imagine dropping the pan and leaving 10 quarts of dirty trans fluid, so the job will cost me around 100 bucks. Im interested in everyones opinion on this, also i was wondering if someone could tell me the correct trans line to disconnect from the radiator (pictures or a link would help).

 

[Mooseman]

I haven't seen anybody write up an article here on doing it so I'll reference the one on TV
Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

I did it 2+ years ago as directed in that article and I have had no problems. I especially liked the "drain it before you pull the pan" trick as it really cuts down on the mess. When I got my truck, it had been abused and neglected. The fluid was brown and skanky so I had to replace it all. Be sure to use Dexron VI since it has better wear and longevity properties. Dexron III is no longer the standard nor regulated by GM.

 

[Shownmyss]

Norcal SS has a write up on this in the "How to" section on the Tbssowners site.

 

[tbuckalew14]

make sure whatever tube you use to drain from the radiator is on tight(mine was not tight enough and ended up with a driveway full of old fluid). Lessen learned I guess.

 

[gmcman]

Search "Trans flush" or "Trans fluid change" There's a few write ups on it.

Passenger side line is the fluid OUT from trans.

 

[STLtrailbSS]

Here's How To Flush Your 4L70E Transmission. - TBSSOWNERS.com Forums - The #1 TrailblazerSS Dedicated Owners Forum

 

[triz]

C'mon get some Amsoil in there! I'm on the same boat as I need to get it done in the next few weeks.

 

[pgibbzz]

Search "Trans flush" or "Trans fluid change" There's a few write ups on it.

Passenger side line is the fluid OUT from trans.

theyre 2 RUBBER lines on the driver side of the radiator, and then theyre 2 steel lines on the bottom side of the radiator, that passenger side? it looks like its threaded in there, how do you put a tube over it. i know that im being nit picky but i like to go over details cause i usually always run into problems on the smallest of details.

 

[gmcman]

If it's not my cell phone it's a crappy PC.. cannot cut and paste. The two lines at the bottom of the radiator, pass side is line out from trans. I belive I stated in my trans fluid change thread that it was 5/16 ID but I think a 3/8 ID hose fits best. You will need to try both, 5/16 is very snug.

 

[pgibbzz]

If it's not my cell phone it's a crappy PC.. cannot cut and paste. The two lines at the bottom of the radiator, pass side is line out from trans. I belive I stated in my trans fluid change thread that it was 5/16 ID but I think a 3/8 ID hose fits best. You will need to try both, 5/16 is very snug.

Ok, disconnect the trans line first THEN start the car in neutral? or vise versa? also to refill do i just dump 13 or however many quarts through the dipstick? is it safe to run the fluid dry then drop the pan?

nevermind, i read moosemans write up. what a great write up mooseman thank you.

 

[Mooseman]

It's not my write up. Was posted long before I ever came on the TB scene. And it has pretty pictures

 

[meerschm]

the two metal lines on the bottom of the radiator carry the transmission fluid. you do not want to unscrew the hex fitting, but disconnect the e-clip. ( make sure you do not bend or loose that clip, you need it to keep the line connected.)

View attachment 30323

this is a photo after I changed my lines.

you pull the little plastic cover back, and there is a wire clip, then the fitting just pulls out. you can do it by hand, or use a tool like this


Lisle 22710 Disconnect Set for Jiffy-Tite Connectors : Amazon.com : Automotive

with the tube disconnected, you can cover the tube with some vinyl hose to catch the fluid.

so why do you want to flush? is the fluid discolored? do you think it has not been changed since the factory? just wondering.

 

[jpimp]

just a heads up the return line from the rad that you want to use is the one on the drivers side

 

[chief0299]

For all you experts...

The old school of thought on flushes was that if your fluid has been in the trans for an extended period or many miles, it wasn't good to do the flush as there was clutch material in the fluid and the fluid had bonded with parts. Flushing at that point would inevitably cause problems

What's the general consenus now?

The reason I ask is because the TB I bought has 140K on it. The trans shifts fine, no slipping, TC goes into lockup with no problems. BUT, the fluid is dark, but not burnt. The previous owner bought it used and has no idea if and when the fluid was ever changed. If I flush and change the filter, what are my chances of starting the fail train moving at this point?

 

[pgibbzz]

the two metal lines on the bottom of the radiator carry the transmission fluid. you do not want to unscrew the hex fitting, but disconnect the e-clip. ( make sure you do not bend or loose that clip, you need it to keep the line connected.)



so why do you want to flush? is the fluid discolored? do you think it has not been changed since the factory? just wondering.

the fluid is discolored and have no clue if it was ever changed, i got the car with 94K and it has 104K. Wasnt planning on keeping the car but unlike most other cars ive owned im gunna see how far i can take it. Also need to do something about the rear differential, the cover is completely rotted and am worried about leakage, the fasteners are bad as well. I hear a "thud" from the rear sometimes when hitting the gas abruptly, like a delayed reaction from the gears.

 

[meerschm]

my opinion: (free advice is sometimes worth what you put into it)

normal service at 100k is to drain pan, wipe out, change filter and refill. if fluid is just discolored, this should be ok, if it smells burnt, i would do the flush.

at your age and location, I suspect you will see some corrosion around the transmission lines, so there is some chance they will start to leak where you get them open, so this is a risk. I changed mine, and it was a bit of a project to get them off the transmission end.

the rear end fluid should be changed, as should the front end, transfer case too,

if you can get the fill and drain out, I would not worrry too much about the cover. ( the fill plug can be a challenge to get out)

 

[meerschm]

For all you experts...

The old school of thought on flushes was that if your fluid has been in the trans for an extended period or many miles, it wasn't good to do the flush as there was clutch material in the fluid and the fluid had bonded with parts. Flushing at that point would inevitably cause problems

What's the general consenus now?

The reason I ask is because the TB I bought has 140K on it. The trans shifts fine, no slipping, TC goes into lockup with no problems. BUT, the fluid is dark, but not burnt. The previous owner bought it used and has no idea if and when the fluid was ever changed. If I flush and change the filter, what are my chances of starting the fail train moving at this point?

if it fails after fluid service, it was headed that way before.

if it was me, I would do the recommended service, drop pan, change filter, clean pan, reassemble and add synthetic dexron VI

 

[Boricua SS]

if it fails after fluid service, it was headed that way before.

if it was me, I would do the recommended service, drop pan, change filter, clean pan, reassemble and add synthetic dexron VI

its a heavily discussed myth on every forum im on... whether the flush harms things or not, im not willing to spend the extra bucks to find out... my DD Grand Prix has 134,xxx miles on it and I just did a tranny service last week... best believe I just did a pan drop, fluid and filter change... same thing on my SS.. even at 30k miles, all I did was a pan drop and a filter/fluid change...

it's your ride... do what eases you the most...

 

[gmcman]

the two metal lines on the bottom of the radiator carry the transmission fluid. you do not want to unscrew the hex fitting, but disconnect the e-clip. ( make sure you do not bend or loose that clip, you need it to keep the line connected.)

Thanks for that. About an hour after I responded, I started thinking....crap, hope he doesn't unscrew the large nut.

Here's my take on the whole trans fluid changeout......

Trans fluid wears out and loses it's additives and varnishes, won't last forever. By changing only 1/4 of the fluid at a 100K interval, the remaining 75% is at the end of it's life. If the trans is not slipping, shifting normal, I would at the very least, change what's in the pan then come back to it about 1-2K miles later and change it all out.

You need to get all the fluid changed, but when you drop the pan and just have a thick smear of dark grey slime in the bottom of the pan, then that's pretty normal for 100K. I don't know how the GM Dex 6 compares to Valvoline Maxlife when at 100K and beyond but Maxlife is good ATF.

 

[gmcman]

just a heads up the return line from the rad that you want to use is the one on the drivers side

This can be done as well, however using a Hayden 397 fitting will make it a lot easier.

http://www.summitracing.com/parts/hda-397/all

 

[Mooseman]

I don't know how the GM Dex 6 compares to Valvoline Maxlife when at 100K and beyond but Maxlife is good ATF.

What type is Maxlife? Dexron III? If it is, it's an outdated standard. GM regulates who can call their fluid Dexron but they don't for Dexron III anymore so anybody can slap a label on their oil and call it that. Dexron VI is certified by GM to meet their standards which are way better than III.

 

[Tofer76]

so what am I looking at for fluid quantity?? to flush and fill say 13 qts or so so say buy a even 4 gal ? that's like 200 bucks for amsoil ! just in fluid,

 

[meerschm]

while the thought of all brand new, clean fluid is attractive,

(like washing the whole car, and steam cleaning the engine, then vacuuming and shampooing the carpet)

the cost is pretty high, esp if you use quality synthetic fluid.

GM maintenance recommendation is to drop pan and change filter.

your choice...

 

[gmcman]

so what am I looking at for fluid quantity?? to flush and fill say 13 qts or so so say buy a even 4 gal ? that's like 200 bucks for amsoil ! just in fluid,

Amsoil is some good fluid, no doubt about it. I however like to change mine out every 30-40K so the cost can really add up. I put Amsoil in the wife's Toyota which has been fine for 70K and I feel good that it's in there.

What type is Maxlife? Dexron III? If it is, it's an outdated standard. GM regulates who can call their fluid Dexron but they don't for Dexron III anymore so anybody can slap a label on their oil and call it that. Dexron VI is certified by GM to meet their standards which are way better than III.

The Maxlife bottle states that it's for vehicles with DexVI. I found prices comparable at Advanced as well as Walmart, I went with 4 gal just to have some extra. I think 12 quarts would work but going with an extra qt bottle isn't as cost-effective as another gal jug, I believe 4 gal was just under $80.

 

[meerschm]

NAPA AUTO PARTS

for an option.

five quarts will be around $40.

filter will be around $20.

 

[triz]

so what am I looking at for fluid quantity?? to flush and fill say 13 qts or so so say buy a even 4 gal ? that's like 200 bucks for amsoil ! just in fluid,

It should run right around 120 dollars for 14 qts. That is of course with a preferred customer membership that you basically get for free from yours truly.

 

[Mooseman]

Looking at their FAQ for the MaxLife Tranny fluid
Valvoline.com > FAQs > System Fluids Car FAQs > Automatic Transmission Fluid

10. Does MaxLife automatic transmission fluid meet Dexron VI specifications?

Yes. MaxLife Dex/Merc ATF meets the Dexron VI specifications.

11. Does GM recognize MaxLife ATF and is this an acceptable fluid to use in place of Dexron VI?

GM only recognizes their factory fill fluid for Dexron VI, but Valvoline meets and exceeds the performance requirements for the specification, and we stand behind the product 100% for this specification.

12. Can MaxLife ATF be mixed with Dexron VI or does the fluid need to be purged prior to installing MaxLIfe ATF?

Valvoline MaxLife Dex/Merc transmission fluid is 100 percent compatible with the Dexron VI for mixing or flushing a system.

So it looks like it does meet Dex VI specs, they just didn't get it recognized by GM.


But Valvoline does have Dex VI spec'd fluid:
Valvoline.com > Products > Automatic Transmission Products > Automatic Transmission Fluid > Valvoline DEXRON® VI ATF

Might be more expensive because of the licensing.


Since out most of our trucks were designed for Dex III (except for 2006+), anything with higher specs will be better.

 

[seanpooh]

If you pay the $10 to Amsoil to become a preferred member, the price drops. Also if you choose a box of 2 2.5 gallons, the price further drops slightly because of packaging/bottles.
And if you get it from a local dealer, no shipping cost but there will be tax.

Also about the fluid color, there was a retired Allison member on the diesel forum site that mentioned that the color doesn't indicate the life of the fluid or how "spent" it is. It's actually to differentiate that red is for the transmission and not to be mixed up with engine, power steering or brake fluid. I believe that's what he said, I'll check my sources.

Found it; "The dye in transmissions is typically pretty stable but will darken with use and will also turn dark from clutch material over time. The color of the fluid (other than being a little annoying) means nothing. It's put into the fluid to distinguish it from engine oil and brake fluid. It's the first requirement of all GM ATF specifications ...... it must be red. Rohm and Haas used to make most of the dyes used in ATFs; not sure that's still the case."

Tom Johnson Transmission Fluids Engineer for Allison Transmission from 1990 to 2009 from Diesel Place

 

[Mark20]

That's what I've always understood. The color is to ID the fluid especially in the case of a leak.

 

[Mooseman]

These two statements contradict each other

The dye in transmissions is typically pretty stable but will darken with use and will also turn dark from clutch material over time.

and

The color of the fluid (other than being a little annoying) means nothing.

Wouldn't it stand to reason that the darker the colour, the longer it has been in service? Or how much clutch material is in the oil and hence, has been "used"?

I think there is a difference between red (light or dark) fluid and dark/brown fluid, the latter meaning it's past its service life.

 

[AbsoluteZero]

I haven't done it yet but recently bought a 12 qt case of Dexron VI from this outfit: Amalie Dexron® VI Synthetic Automatic Transmission Fluid – 12QT case
$68/12 qt ($5.67/qt). I ordered the case on a Fri and UPS delivered on Wed - Indiana to Arizona. I've never hear of Amalie Oil but stumbled on it on Amazon. I plan on using a method similar to that posted on TBSSowner's forum. I've got a 5 gal bucket with a large Home Depot paint stirring stick with calibration marks so I know what's been pumped out. Probably a minor difference in procedure, I planned on dumping the drained fluid into the 5 gal bucket to account for the new fluid replaced in the pan. That way I could account for the total amount of new fluid exchanged with the old. Again minor. What I don't know is if fluid can be poured into the fill tube as fast as it's pumped out. Sounds like not.

 

[Mooseman]

Never heard of them neither but it is licensed by GM so it had to meet their DexVI specs.

 

[triz]

Looks like they have not been around for too long. 5 years or so. But looks like people like it.

 

[AbsoluteZero]

When I first found the link to the online store it wasn't apparent if there was a shipping cost so I emailed the link and inquired. On orders greater than $40 shipping is included in the price. (some like to say free!) Under $40 it's a flat $16. The response to my inquiry was prompt. A partial response about Amalie was: "Amalie has been around since 1903. Has always been a high quality oil. We've just never done a great job marketing it until recently.
Amalie is made in Tampa, Fla. and we operate the online store as part of an agreement with Terry McMillen's Top Fuel NHRA drag racing team which is based in Elkhart, Ind.
You can learn more about Amalie at Amalie Oil Co. and Terry at http://terrymcmillen.com"
I have no personal experience with the produce. I've done a couple pan refills and filter exchanges during the Envoy's 117k life but thought I'd do a fluid exchange using Dexron VI

 

[Mark20]

These two statements contradict each other



and



Wouldn't it stand to reason that the darker the colour, the longer it has been in service? Or how much clutch material is in the oil and hence, has been "used"?

I think there is a difference between red (light or dark) fluid and dark/brown fluid, the latter meaning it's past its service life.

I don't think the color or shade is calibrated to service life but you can get a good hint as to where things are.

 

[seanpooh]

Yeah... I think what he was trying to say is that no matter the variation of color of the transmission fluid, it's not an indication of time to change.

For example, engine oil. Starts off golden (purple in the case of Royal Purple) and then darkens to black. Black doesn't mean it's time to change, just more soot but a good indication to change.

The engineer also stated that it was "OK" to put Transynd into our 4L60e which I plan on doing soon. It is a synthetic and has additives good enough for Allision trannys, so why not. I don't see the harm. I figure that our trannys were built for the DexIII so Transynd should cover that basis.

 

[smt 59]

Hi all,
I have been reading all the information about changing oils etc. and my thoughts are that changing fluids in the drive train is better more often than not, why wait for failure. For the cost of changing these oils it is going to be benificial in the long run, I use Amsoil for all the fluid changes except the transfer case that has the GM specific lube(synthetic I believe), the owners manual also mentions synthetic oils as well. For the transmission you will not empty all fluid out by dropping the pan so what I did was a flush and drove for 3,000,kms then did the pan drop. Just my thoughts and what I would do( a couple of hundred dollars is cheap compared to repair and or replacement.)
PS, this is my first reply on this web site, be gentle on me!!!!

 

[meerschm]

Hi all,
I have been reading all the information about changing oils etc. and my thoughts are that changing fluids in the drive train is better more often than not, why wait for failure. For the cost of changing these oils it is going to be benificial in the long run, I use Amsoil for all the fluid changes except the transfer case that has the GM specific lube(synthetic I believe), the owners manual also mentions synthetic oils as well. For the transmission you will not empty all fluid out by dropping the pan so what I did was a flush and drove for 3,000,kms then did the pan drop. Just my thoughts and what I would do( a couple of hundred dollars is cheap compared to repair and or replacement.)
PS, this is my first reply on this web site, be gentle on me!!!!

welcome,



feel free to post whatever you are interested in.

you can fill in your profile with vehicle details if you like.

 

[Stuntmanmike77]

If you just do a pan drop, will the new dexron vi mesh with the old fluid? I can keep draining and hopefully replacing all the old fluid over time cause mine has a drain plug on it.

 

[Mooseman]

New fluid is compatible with the old stuff. Still better to do via the flush method, if just to drain it. Avoids a lot of the mess when you drop the pan.