# Automatic Transmission Flush



## Robby (Mar 1, 2013)

IF.....the fluid was actually 'black' it is indicating a problem already exists.....trans fluid gets burned when clutch's slip, not through normal usage.
I doubt if your fluid was burned, otherwise you would be asking about other problems.
Service writers are taught by BG to say this if asked....they likely never saw the fluid.

The filter can only be exchanged if the trans case is 'split' for service....it would have to be out of the car for this.....so, per Chevrolet, the filter is considered a 'Life of Transmission' component.

This leads us to 'Why is flushing not recommended by the manufacturer?'

Any debris that was dislodged....debris that was causing no harm where it was, now has been freed up to potentially restrict the non serviceable filter......with that, the potential of a pressure restriction causing the clutch's to slip.....burning them and the fluid.....and then, around we go....now, for sure the fluid is black and the trans requires reconditioning which will get you a nice new filter.

OK, enough doom and gloom......if the trans was shifting fine, the odds are favorable that you'll be fine.
But for future knowledge, no manufacturer recommends flushing and all caution against it........they have seen too many failures that were a result of the process, so..........

Rob


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## Tomko (Jun 1, 2013)

It is controversial that's for sure. 

I have read an internal GM document advising never to introduce anything other transmission fluid into a transmission. 

Dexron VI is such a highly improved fluid over the previous Dexron III-H that I would never do it. Many, if not all, of these flushes predate Dexron VI. They had their purpose. Today I'm not so sure. 

But that's my opinion. There will be others.


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## Snappa (Mar 31, 2013)

So pretty much I paid to do something that is not supposed to be done? These people are just a bunch of criminals out here. But two can play at that game. Makes me want to drain it and run it for a while and intentionally burn it up and refill it and have them replace it under warranty. Then say hey I really think your flushing procedure caused an issue. And does it count that the service advisor randomly said it was black without me even asking?


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## Snappa (Mar 31, 2013)

But also in theory, no actual pressure is being introduced to the system outside of the pressure the automatic transmission itself produces. It uses this pressure to simply push the fluid out of one cooler line and then new fluid comes back in into the other line. It does this at a rate where the transmission never gets below the threshold of the amount of fluid it should have. So basically the machine is replacing the transmission cooler for that moment. So if any filter was to get clogged up or whatever, that would be already done by the transmission it's self then: right?


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## Robby (Mar 1, 2013)

Snappa said:


> So pretty much I paid to do something that is not supposed to be done? These people are just a bunch of criminals out here. But two can play at that game. Makes me want to drain it and run it for a while and intentionally burn it up and refill it and have them replace it under warranty. Then say hey I really think your flushing procedure caused an issue. And does it count that the service advisor randomly said it was black without me even asking?


Although I understand your frustration with the dealer, just take it as a lesson learned.

Always refer to your owners manual.......at no time will you see the word 'Flush' used for any service other than sometimes coolant....depending on brand.......and brake fluid.

Any dealer that has a service menu board with recommended services beyond or in addition to the recommendations in your manual should automatically be considered a likely rip off house.......hold your wallet tight.

Rob


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## Tomko (Jun 1, 2013)

A machine implies machinery. What you describe are two reservoirs. Not a machine.


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## Robby (Mar 1, 2013)

Snappa said:


> But also in theory, no actual pressure is being introduced to the system outside of the pressure the automatic transmission itself produces. It uses this pressure to simply push the fluid out of one cooler line and then new fluid comes back in into the other line. It does this at a rate where the transmission never gets below the threshold of the amount of fluid it should have. So basically the machine is replacing the transmission cooler for that moment. So if any filter was to get clogged up or whatever, that would be already done by the transmission it's self then: right?


In theory, yes,the pressure is the same, however, a cleaning agent was introduced for the purpose of dislodging any accumulated debris....not a good thing had there been any significant amount of 'stuff....like clutch shear off' get deposited on/in the filter.

Like I said though......you were not having any problem so the odds of material/debris in the case is unlikely.......just avoid the process in the future.....this car or any subsequent.

Rob


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## Snappa (Mar 31, 2013)

I just we watched a video on the "machine" and it doesn't induce any pressure. All it is inside is a container that that has a diaphragm inside of it. On one side of the diaphragm you have the ATF from the car being pumped at the same pressure as the system always pumps it. On the top half of the diaphragm how simply have the new fluid sitting on top that has been filled at the recommended specifications. The old fluid pushing onto the diaphram pushes this new fluid into the other cooler line. All of this is done to maintain the exact same pressure as if w automatic transmission was just running as normal and just pumping into the cooler. There is however one feature that does employ an electric pump for lower flow/pressure transmissions to get the process to go faster. Now wether they had to use this on the Cruze transmission idk, but that is the only actual added pressure to the whole process and it's very slight. Regardless I won't have them do this again since there is so much debate everywhere about them. I knew all along it only says drain, I just assumed going to a gm dealership , that is what their service entailed. It didn't go into the details of what's actually done until I got the papers back. I've never had any problems with this dealership and they actually seem honest about their services or maybe accidentally saying the right words. Because another recommended service was a coolant flush. This car actually does require an actual coolant flush at 150,000 miles, per manual. I'm no where near that but my Cruze is a 2011 and it also says to do that at 5 years old, whichever comes first. They didn't try to shove this service down my throat, I just happened to see it printed on the back of one of my invoice papers for future reference.


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## Robby (Mar 1, 2013)

Regarding coolant.....5 years or 150k miles.....I wish they wouldn't give a mileage suggestion......mileage has no effect on coolant.
The issue is time.....over time, the coolant becomes acidic and the change is recommended to keep the coolant from causing cooling system corrosion.

I recommend every four or five years regardless of mileage......

Rob


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## jsusanka (Jan 31, 2011)

The only time I have seen a flush cause problems was when nothing was done to the transmission and then at 100,000 miles a flush was done and they ended up needing a new transmission. 

I think if you keep up with the flushes from when the car was new you will be fine and the transmission will be fine. 

We have a 2007 mazda 3s that we bought new and have had the dealer do a flush every 30,000 miles and the it still shifts like it did when we bought it and it has 103,566 miles. This last flush I had them put in Amsoil so I may go 60,000 on that if we still own the car. I tend to go with what the car manufacturer suggests and how to do the work. 

I had my Cruze flushed at around 35,000 miles and had Amsoil installed via the dealer where I bought the car. I will probably get it flushed again between 70,000 and 80,000 miles and refilled with Amsoil. You would of thought someone would of invented an easy way to exchange all the fluid and filter in the automatics by now. I think the 100,000 miles non-severe service that the owners manual suggests is way too long to go without any kind of fluid exchange.

I think you will be fine. But I would get your coolant changed. Five years is pushing it with coolant. I am on my fourth water pump so coolant is one thing I haven't had to worry about changing lol.


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## Snappa (Mar 31, 2013)

So do they do a complete flush when installing a new water pump? Or is it just a topping off? I had to have the thermostat replace under warranty. Would they have drained and refilled then as well?


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## jsusanka (Jan 31, 2011)

Snappa said:


> So do they do a complete flush when installing a new water pump? Or is it just a topping off? I had to have the thermostat replace under warranty. Would they have drained and refilled then as well?


From what I have seen on my tickets every time they replace the water pump they replace all of the coolant. I think with a water pump they have to pretty much lose all the coolant but I don't know about a thermostat and if they are able to contain the loss of coolant. I just had the water outlet replaced but I don't think they had to drain all the coolant but I did not care because it was new coolant anyway because I had a water pump replaced last year and the water outlet was replaced under the power train warranty.


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## anthonysmith93 (Jul 15, 2015)

jsusanka said:


> The only time I have seen a flush cause problems was when nothing was done to the transmission and then at 100,000 miles a flush was done and they ended up needing a new transmission.
> 
> I think if you keep up with the flushes from when the car was new you will be fine and the transmission will be fine.
> 
> ...


It must be car/trans dependent, because I had a 2005 Malibu LS that went on factory trans fluid until 180,000 miles before I ever had it serviced (flush n fill). It didn't fix the intermittent issue I had with a first to second gear slip, guess it was common on those cars and the G6, but it didn't make it any worse either...although I was worried since it had never been serviced new issues would arise...that luckily wasn't the case.


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## XtremeRevolution (Jan 19, 2012)

There is a great deal of misinformation, misunderstanding, and fear mongering with the use of the term "transmission flush." It is used for many different service types. 

The current methods I am aware of allow the transmission's internal pump to cycle old fluid out, while a "machine" cycles new fluid in. This "flush" method is 100% safe, and is a far better approach than a drain and refill (which only replaces less than 50% of the fluid each time it is performed), as it replaces almost 100% of the fluid in one run. 

The reason the transmission flush has a poor reputation is due to the use of dex3 fluids, which were far lower quality than the dex6 fluids we have today, being serviced in transmissions that were WELL past their required service life. Those owners typically brought in transmissions that were having shifting issues, expecting the fluid to resolve those issues. The damage had already been done by that point, and the transmission flush did not prevent the impending total failure from occurring. Another reason is due to pressure-fed flush machines that did not utilize the internal pump to cycle fluid through, which could dislodge oxidation deposits left behind by the aforementioned poor quality dex3 fluids, which would then clog up very small valve body passages. This again is the failure of the customer in maintaining their transmission at proper intervals, not the flush method itself, as those deposits do not form when the correct service intervals and driving conditions are followed. In those times, owners who expected to tow regularly were also advised to install auxiliary transmission oil coolers to keep the dex3 spec fluids from breaking down under heat. 

I have a tutorial written for performing this "flush" in your own garage, provided you have a method to scan for transmission temp. I've had several mildly technical owners perform this process safely and very effectively, with excellent results, using AMSOIL Signature Series ATF. 

Since most of these pressure-fed machines have been decommissioned due to their reputation and replaced by machines that simply replace fluid expelled by the transmission's internal pump, they are no less "safe" than a standard drain and refill, but they do waste less fluid while replacing a far greater percentage of the old fluid. If you fail to service your transmission at the required intervals, neither method is guaranteed not to reveal more problems that would have already been caused. 

With respect to these specific transmissions, GM used corrosion inhibitors to prevent internals from rusting during storage at dealer lots, which turned the oil black and also compromised shift quality. I was told that they stopped using these corrosion inhibitors at some point, but the color of the fluid is a consequence of these corrosion inhibitors, not the break-down or oxidation of the fluid itself. Color is *NOT *an accurate or reliable metric of the condition of a lubricant.


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## spacedout (Dec 7, 2010)

XtremeRevolution said:


> The reason the transmission flush has a poor reputation is due to the use of dex3 fluids, which were far lower quality than the dex6 fluids we have today, being serviced in transmissions that were WELL past their required service life. Those owners typically brought in transmissions that were having shifting issues, expecting the fluid to resolve those issues. The damage had already been done by that point, and the transmission flush did not prevent the impending total failure from occurring.


Even with the better fluid today, most people overlook transmission fluid service entirely. Like you said they finally do when the damage is already done. I didn't change my cruze trans fluid until 74,000 miles, It was 2 quarts low at 94,000 from a leaking trans cooler line(part of the reason I traded). With my new sonic I plan to change the trans fluid every 35,000-40,000 miles. 




anthonysmith93 said:


> It must be car/trans dependent, because I had a 2005 Malibu LS that went on factory trans fluid until 180,000 miles before I ever had it serviced (flush n fill). It didn't fix the intermittent issue I had with a first to second gear slip, guess it was common on those cars and the G6.


My 2004 Cavalier had "lifetime fill" fluid, requiring no service. Even so At 65,000 miles I paid to get new fluid and filter. At 110,000 miles the trans still shifted like new(no slippage). I believe this car used the same transmission your Malibu did(if yours was a 2.2L Ecotec).


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## ChevyGuy (Dec 13, 2014)

Robby said:


> Regarding coolant.....5 years or 150k miles.....I wish they wouldn't give a mileage suggestion......mileage has no effect on coolant.
> The issue is time.....over time, the coolant becomes acidic and the change is recommended to keep the coolant from causing cooling system corrosion.
> 
> I recommend every four or five years regardless of mileage......


It seems I've heard of a way of testing the coolant with a volt meter, but I don't remember the details.


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## Robby (Mar 1, 2013)

ChevyGuy said:


> It seems I've heard of a way of testing the coolant with a volt meter, but I don't remember the details.


I have heard of using a voltmeter as well.....never tried it though.

We get litmus strips from Caterpillar at my sons shop......just dip and color check every year but we change coolant at the fifth year regardless of the strip........we just like to see if somethings going on prior to the five year point.

Rob


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## anthonysmith93 (Jul 15, 2015)

spacedout said:


> XtremeRevolution said:
> 
> 
> > The reason the transmission flush has a poor reputation is due to the use of dex3 fluids, which were far lower quality than the dex6 fluids we have today, being serviced in transmissions that were WELL past their required service life. Those owners typically brought in transmissions that were having shifting issues, expecting the fluid to resolve those issues. The damage had already been done by that point, and the transmission flush did not prevent the impending total failure from occurring.
> ...


I had the v6 3.5L Malibu..which I guess shared the same motor/trans as the G6 at certain trim levels


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## TurboDieselCruze2014 (Jan 23, 2020)

Robby said:


> IF.....the fluid was actually 'black' it is indicating a problem already exists.....trans fluid gets burned when clutch's slip, not through normal usage.
> I doubt if your fluid was burned, otherwise you would be asking about other problems.
> Service writers are taught by BG to say this if asked....they likely never saw the fluid.
> 
> ...


Do you know if you replace the trans fluid on a Cruze do you have to reset anything in terms of OBD? Or do you just flush, replace and go about your business.


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## Robby (Mar 1, 2013)

Just change the fluid.....nothing additional is required.

Rob


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