Drain/refill vs diy flush?

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Later model Toyota's don't have a dipstick. Fluid check plug and a drain plug. My 15 Tacoma I did my own flush. Now I just change the fluid that's in the pan every 30-60K.
 
Originally Posted by KrisZ
Again, here is a study that shows contaminants in the ATF make the clutch pack surface smoother. I have yet to see a study showing the opposite. Why are people repeating that contaminants in ATF are beneficial?

Originally Posted by KrisZ
Here is a pretty good study of wet clutch degradation.

It has an interesting findings about clutch surface roughness and how it compares from brand new vs. after the tests were done.
From that study, it looks like the contaminants actually contribute to making the clutch surface smoother by filling in the pores.

Quote
The average surface roughness from the surface profile measurements before the tests is 9.52 â€Î¼m and after the tests it is â€1.94 μm. The average skewness before the test is -0.87 and after the test it is -3..4 .
Figures 4 and 5 clearly show that the friction material has become smooth and flat after the tests, which indicates that the friction material has degraded during the tests. One can also notice in Figure 4 that the surface of the friction material before the tests is more porous compared to after the tests. The reduction of the surface porosity is believed to be caused by the pores blocking [7, 8], resulting from the deposition of debris particles of the friction material and/or degradation products of the ATF.




https://www.hindawi.com/journals/isrn/2013/607279/



You are answering the question that isn't being asked. Nobody is questioning if fine metal contaminants are smoothing the clutch packs, the question is if those contaminants aid WORN (smooth) disc in maintaining friction vs fresh fluids with very little contaminants. Who needed a study to determine contaminated fluid wears the friction surfaces of the disc pack. That's why we change it so they don't get smooth. The question is will putting new slippery fluid with a smooth WORN clutch pack cause slipping vs old contaminated less slippery fluid. Anecdotal experience (and I mean immediately not 3,4,5 weeks/months later) leaves no doubt in my mind adding all new non contaminated fluid only makes a transmission on the brink of slipping....slip.
 
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Originally Posted by BMWTurboDzl
Originally Posted by KrisZ
Originally Posted by stanlee
Originally Posted by fireman1073
#2 Although the clutches are worn there is clutch material floating around in the existing ATF which assists with shifting. A flush removes this material so shift problems occur.

never heard that before


I can't believe you guys have never heard of these things. Basically once you've neglected your transmission and worn out the clutches by not changing the fluid, the metals and grit accumulated within the fluid act as friction modifiers on the worn disc (and if you've ever cleared the pan magnet on any automatic transmission you know plenty of metal makes its way into the fluid). Same concept as Lucas transmission fix. Same concept as Fords required friction modifiers for their limited slip clutch style diffs. You put in all new slippery low friction fluid and the disc wont hold.This isn't even that uncommon with pan drop changes much less flushing all the old fluid out. NONE of these principles obviously apply to well maintained and/or non worn out in proper working order.


It's an assumption based on good sounding reasoning but with little facts behind it, other than the correlation with new fluid and transmission failure shortly afterwards. If the old fluid, full of clutch material contaminates was truly helping with clutch engagement because it has an increased friction properties, why would the clutch pack wear out faster in the first place? Why would keeping the fluid fresh and "more slippery" help with clutch pack life? The opposite should be observed if that were the case.

My personal opinion is that contaminated fluid affects the solenoid operation and seals some of the leakage through these solenoids. But the solenoid wear is cause by the contaminants and causes them to slip the clutches more than they normally would, hence clutches wear out faster if the fluid is contaminated. Once new fluid is introduced and the contaminants are cleaned a bit, the extra leakage at the solenoids causes pressure drop and the clutches start slipping.


Context is important here. In this particular case Stanlee(rip) and myself are speaking about a neglected transmission. My understanding is that with todays mechtronics a transmission is able to make adjustments up to a certain degree.

The problem is that, just like with 3k mile oil changes, there's no proof the frequent exchanges or pan drops will prolong the life of the transmission. It's ALL ANECDOTAL.

Like I said early from what I've been told by people who actually work on transmissions is that it's basically a crap shoot as in it's the design not the frequency of fluid changes which predominately figure into the lifespan of the unit.



This is very ignorant of the many transmissions that have solenoids that suffer horribly from contaminant buildup.
 
I don't follow the quoted logic of fluid changes don't help with AT life cycles. Just like a lot of members here change their oil too often and dispute 20 decades of data proving this on this forum their are excuses for everyday of the week to change $10 a quart synthetics at 5K intervals there are excuses to change modern ATF's at 30K when there is data showing it will go 3X this and still be serviceable. But not changing does not past the smell test. Will the transmission work at 100K on original fluid yeah it may make it to 150K but past this I doubt. I am more confident if the ATF has been changed twice by the 150K mile point it will make it to 200K.
 
Originally Posted by stanlee

You are answering the question that isn't being asked. Nobody is questioning if fine metal contaminants are smoothing the clutch packs, the question is if those contaminants aid WORN (smooth) disc in maintaining friction vs fresh fluids with very little contaminants. Who needed a study to determine contaminated fluid wears the friction surfaces of the disc pack. That's why we change it so they don't get smooth. The question is will putting new slippery fluid with a smooth WORN clutch pack cause slipping vs old contaminated less slippery fluid. Anecdotal experience (and I mean immediately not 3,4,5 weeks/months later) leaves no doubt in my mind adding all new non contaminated fluid only makes a transmission on the brink of slipping....slip.


Ah, but I am.
You cannot have particles smoothing the clutch surface, reducing its coefficient of friction and at the same time increase that coefficient of friction somehow. Which is what some of you are saying here. By what mechanism I have no clue.
If you have particles small enough to fill in the pores of friction material and make it smooth, how can they increase friction? In order to increase friction they would have to embed themselves in such a way that the clutch surface would be rougher, not smoother. Hence I posted the study.
 
Going through this again:

1. ATF changes per the manufacturer's intervals and/or usage requirements are best for transmission longevity
2. If you do it regularly you can completely replace it with a pressure machine and typically without any issue
3. If you don't change ATF according to schedule, the contaminants and particulates will build up and degrade the transmission components
4. Once that degradation has already occurred and there is high mileage on the ATF, changing out the ATF with a pressure machine may dislodge more particulates that had settled into cavities, and the fresh ATF may clean/loosen yet additionally more particulates, and these two actions working together may clog the critical orifices because it puts more particulates in circulation than previously with the old ATF. So even though you have better fluid you now have more contaminants in circulation and wear is significantly increased and transmission function is compromised to the point of failure in a short time after a flush.
5. The drain and refill process will not dislodge particulates from pressure flow and will clean everything much more slowly allowing the filter to take it out. Also each time there is a subsequent drain and refill contaminants are coming out with the fluid change. The contaminants are slowly removed and the ATF is slowly refreshed.

The contaminant study cited has little advisory relevance as to whether you should flush or drain/refill an overly "neglected" transmission because that was not the point of the study. It simply shows that contaminants degrade components--well I think we all knew that.That study would argue for following the correct service intervals to remove contaminants for transmission longevity. This is why I quoted a Pennzoil service statement because comes closer to addressing the pertinent issue. They say any time you change neglected fluid there is risk. That is the same as saying new fluid on degraded components is not a high risk. They simply are stating what many manufacturers also believe--that because there is that risk--there will be less exposure to failure from a gradual drain/refill process.

I suppose the point could be debated as to whether from a pure lubricity standpoint whether a degraded/contaminated fluid used on degraded components will provide a better coefficent of friction than a fresh fluid on degraded components. While particulates will degrade components, once that degradation has occurred to certain point, the degraded/contaminated fluid may still provide better friction on those components than fresh fluid might with more lubricity might on a degraded component. It's understood that fresh fluid on a sound component will provide better friction than contaminated fluid. I didn't note the cited test proving that fresh fluid is better on a worn component. But even if it is proven--the reality is that a flush and the subsequent aggressive cleaning from the new ATF will still likely introduce more contaminates into circulation than with old fluid and therefore hasten the transmission's demise.
 
Originally Posted by KrisZ
Originally Posted by stanlee

You are answering the question that isn't being asked. Nobody is questioning if fine metal contaminants are smoothing the clutch packs, the question is if those contaminants aid WORN (smooth) disc in maintaining friction vs fresh fluids with very little contaminants. Who needed a study to determine contaminated fluid wears the friction surfaces of the disc pack. That's why we change it so they don't get smooth. The question is will putting new slippery fluid with a smooth WORN clutch pack cause slipping vs old contaminated less slippery fluid. Anecdotal experience (and I mean immediately not 3,4,5 weeks/months later) leaves no doubt in my mind adding all new non contaminated fluid only makes a transmission on the brink of slipping....slip.


Ah, but I am.
You cannot have particles smoothing the clutch surface, reducing its coefficient of friction and at the same time increase that coefficient of friction somehow. Which is what some of you are saying here. By what mechanism I have no clue.
If you have particles small enough to fill in the pores of friction material and make it smooth, how can they increase friction? In order to increase friction they would have to embed themselves in such a way that the clutch surface would be rougher, not smoother. Hence I posted the study.







They aren't increasing the coefficient. They are continually wearing the disc just like you and the study said (and will eventually cause it to skip on it's own). But we aren't talking about that fluid or the disc coefficient. We are talking about the NEW uncontaminated fluid immediately lowering friction coefficient enough to cause slipping.
 
Originally Posted by KrisZ
Originally Posted by stanlee

You are answering the question that isn't being asked. Nobody is questioning if fine metal contaminants are smoothing the clutch packs, the question is if those contaminants aid WORN (smooth) disc in maintaining friction vs fresh fluids with very little contaminants. Who needed a study to determine contaminated fluid wears the friction surfaces of the disc pack. That's why we change it so they don't get smooth. The question is will putting new slippery fluid with a smooth WORN clutch pack cause slipping vs old contaminated less slippery fluid. Anecdotal experience (and I mean immediately not 3,4,5 weeks/months later) leaves no doubt in my mind adding all new non contaminated fluid only makes a transmission on the brink of slipping....slip.


Ah, but I am.
You cannot have particles smoothing the clutch surface, reducing its coefficient of friction and at the same time increase that coefficient of friction somehow. Which is what some of you are saying here. By what mechanism I have no clue.
If you have particles small enough to fill in the pores of friction material and make it smooth, how can they increase friction? In order to increase friction they would have to embed themselves in such a way that the clutch surface would be rougher, not smoother. Hence I posted the study.







They aren't increasing the coefficient. They are continually wearing the disc just like you and the study said (and will eventually cause it to skip on it's own). But we aren't talking about that fluid or the disc coefficient. We are talking about the NEW uncontaminated fluid immediately lowering friction coefficient enough to cause slipping. On disc not worn out the NEW fluid doesn't lower friction coefficient enough to cause slipping but on worn disc it's a different story.
 
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Correcting a previous typo because the edit function time out:

Quote
[/quote]This is why I quoted a Pennzoil service statement because comes closer to addressing the pertinent issue. They say any time you change neglected fluid there is risk. That is the same as saying new fluid on degraded components is not a high risk. They simply are stating what many manufacturers also believe--that because there is that risk--there will be less exposure to failure from a gradual drain/refill process.
Should be: That is the same as saying new fluid on degraded components IS a high risk.
 
Originally Posted by T-Stick


Should be: That is the same as saying new fluid on degraded components IS a high risk.


And I'm not disputing that. There is obviously a risk when changing the ATF on a neglected transmission and there is more then enough evidence of this. What I'm disputing is the mechanism that the contaminators in the fluid help keeping the clutches engaged. There is absolutely no scientific basis for this, nor any studies that I have seen. This talk seem to have started with people posting few youtube videos on the subject and it now is taken almost as a fact.

Like I mentioned earlier, in order for particles to help with clutch engagement, they would have to permanently embed themselves into the clutch material in such a way that it would make that surface rougher, which I proved by posting a study that opposite is happening. Since clutch pack engagement is a mechanical coupling, not a fluid coupling, contaminants floating around have no effect on the friction when the clutches are fully engaged, because these contaminants have no anchor point. It's like having sand between two sliding surfaces. Go ahead and grab two pieces of 2x4 and start rubbing them together, now throw some fine sand on them and repeat. You will find sand creating an air gap and rolling around, thus reducing friction, because the sand particles have no anchor point.
Or let me put it this way, why spend money on sand paper right? Just get some paper, throw in some sand on it and viola! Except it doesn't work this way.


What I'm trying to explain is that a traditional, modern automatic transmission is a very complex hydraulic system and ATF is at its heart. Pretty much every automatic transmission since mid to late 90s is controlled by electromagnetic solenoids, ECU and has some sort of adaptive logic. Clutch packs are engaged/disengaged by hydraulic action alone, not like traditional manual clutches where constant spring pressure applies the clamping load. Controlling clutches hydraulically has advantages, the pressure can be adjusted on the fly, making slow and smooth shifts when driven normally, or fast and hard when accelerating at WOT. This logic also adapts to changing conditions, like aging ATF or slower acting control valves.

Now, when a severely worn out, burnt, sheared out and full of contaminants ATF is changed with a brand new one, all of these calibrations are wrong, right away. Then you have the effect of contaminants migrating because the new ATF can now hold more and also creates a cleaning action. So these contaminants can be removed from one place and deposited somewhere else, where before everything was sort of settled down.

Since hydraulic pressure and its control is so vital to the clutch pack operation, my position is that the new fluid creates an "upset" in the system through various mechanisms, not just one, that the pressure cannot be regulated properly and therefore the transmission starts slipping shortly afterwards.

Edit:
To add to the above, I believe that resetting the AT ECU might provide some advantage when a neglected transmission is serviced. But It's only my speculation and at best it would probably only delay the inevitable.
 
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Originally Posted by KrisZ
Originally Posted by T-Stick


Should be: That is the same as saying new fluid on degraded components IS a high risk.


And I'm not disputing that. There is obviously a risk when changing the ATF on a neglected transmission and there is more then enough evidence of this. What I'm disputing is the mechanism that the contaminators in the fluid help keeping the clutches engaged. There is absolutely no scientific basis for this, nor any studies that I have seen. This talk seem to have started with people posting few youtube videos on the subject and it now is taken almost as a fact.


I recall hearing this back in the early '90's. I think the myth was in place long before we had youtube to cook up new myths.

Quote

What I'm trying to explain is that a traditional, modern automatic transmission is a very complex hydraulic system and ATF is at its heart. Pretty much every automatic transmission since mid to late 90s is controlled by electromagnetic solenoids, ECU and has some sort of adaptive logic. Clutch packs are engaged/disengaged by hydraulic action alone, not like traditional manual clutches where constant spring pressure applies the clamping load. Controlling clutches hydraulically has advantages, the pressure can be adjusted on the fly, making slow and smooth shifts when driven normally, or fast and hard when accelerating at WOT. This logic also adapts to changing conditions, like aging ATF or slower acting control valves.

Now, when a severely worn out, burnt, sheared out and full of contaminants ATF is changed with a brand new one, all of these calibrations are wrong, right away. Then you have the effect of contaminants migrating because the new ATF can now hold more and also creates a cleaning action. So these contaminants can be removed from one place and deposited somewhere else, where before everything was sort of settled down.

Hmm, that is food for thought--that calibration and/or adaptive learning might be borked by changing the fluid. I hadn't thought of smart transmissions.

I still think that dumping old fluid in one fell swoop is best. If the transmission goes afterwards--it probably was on its way out anyhow. Correlation isn't causation and all.
 
Originally Posted by supton
[

I recall hearing this back in the early '90's. I think the myth was in place long before we had youtube to cook up new myths.

I don't recall it being repeated on BITOG, that's what I meant, sorry for not being clear on that. It seems some BITOG posters picked up on this after someone posted a ChrisFixit youtube video.
 
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Originally Posted by T-Stick
Jim D. Stokes, manager of technical services for Pennzoil, a leading supplier of ATF, issued a service bulletin advising shops about the risk. Included with the advisory is this sample waiver:

Waiver and Release Automatic Transmission Service

We strongly recommend that automatic transmission service should not be performed on any vehicle that has not had its automatic transmission serviced within the last 60,000 miles. We will perform automatic transmission service on such vehicles at the customer's request only if this waiver and release is signed by the customer:

I acknowledge and fully understand that my motor vehicle's records indicate that its automatic transmission has not been serviced within the last 60,000 miles, that this fact was pointed out to me and that I willingly requested (name of installer) to service the transmission.

Due to the fact that my vehicle's transmission was not serviced within the last 60,000 miles, and understanding that servicing such a transmission may cause damage to my vehicle, I hereby agree that I will not hold (installer) responsible for any damage caused by any transmission service performed on my vehicle. I hereby fully release (installer) from any claims by me or others on my behalf and hereby waive any rights to make any claims against (installer) for any damage to my motor vehicle caused by any transmission services performed on my vehicle.

Signed:

Date:


https://www.chicagotribune.com/news/ct-xpm-2000-03-12-0003120058-story.html


There is a Scotty Kilmer video where he screams a similar sentiment.

....where's the drain/refill and throw in some Lubegard Red or Platinum?
 
Originally Posted by KrisZ
Originally Posted by T-Stick


Should be: That is the same as saying new fluid on degraded components IS a high risk.


And I'm not disputing that. There is obviously a risk when changing the ATF on a neglected transmission and there is more then enough evidence of this. What I'm disputing is the mechanism that the contaminators in the fluid help keeping the clutches engaged. There is absolutely no scientific basis for this, nor any studies that I have seen. This talk seem to have started with people posting few youtube videos on the subject and it now is taken almost as a fact.

Like I mentioned earlier, in order for particles to help with clutch engagement, they would have to permanently embed themselves into the clutch material in such a way that it would make that surface rougher, which I proved by posting a study that opposite is happening. Since clutch pack engagement is a mechanical coupling, not a fluid coupling, contaminants floating around have no effect on the friction when the clutches are fully engaged, because these contaminants have no anchor point. It's like having sand between two sliding surfaces. Go ahead and grab two pieces of 2x4 and start rubbing them together, now throw some fine sand on them and repeat. You will find sand creating an air gap and rolling around, thus reducing friction, because the sand particles have no anchor point.
Or let me put it this way, why spend money on sand paper right? Just get some paper, throw in some sand on it and viola! Except it doesn't work this way.


What I'm trying to explain is that a traditional, modern automatic transmission is a very complex hydraulic system and ATF is at its heart. Pretty much every automatic transmission since mid to late 90s is controlled by electromagnetic solenoids, ECU and has some sort of adaptive logic. Clutch packs are engaged/disengaged by hydraulic action alone, not like traditional manual clutches where constant spring pressure applies the clamping load. Controlling clutches hydraulically has advantages, the pressure can be adjusted on the fly, making slow and smooth shifts when driven normally, or fast and hard when accelerating at WOT. This logic also adapts to changing conditions, like aging ATF or slower acting control valves.

Now, when a severely worn out, burnt, sheared out and full of contaminants ATF is changed with a brand new one, all of these calibrations are wrong, right away. Then you have the effect of contaminants migrating because the new ATF can now hold more and also creates a cleaning action. So these contaminants can be removed from one place and deposited somewhere else, where before everything was sort of settled down.

Since hydraulic pressure and its control is so vital to the clutch pack operation, my position is that the new fluid creates an "upset" in the system through various mechanisms, not just one, that the pressure cannot be regulated properly and therefore the transmission starts slipping shortly afterwards.

Edit:
To add to the above, I believe that resetting the AT ECU might provide some advantage when a neglected transmission is serviced. But It's only my speculation and at best it would probably only delay the inevitable.


This is a very well reasoned post and worthy of consideration. You also are noting some of the same points I was making. The only point of further consideration for me would be seeing more than one test concerning whether contaminants always cause more slippage. If so, then all new fluid at one time is very bad because it will clean up and circulate more of them and thus hasten the demise. I see the bottom line essentially the same - the drain refill is the preferred method for trying to salvage a neglected transmission because you can't introduce too much new fluid and cleaning at once and you need to remove those contaminants through a series of drains. I have never had a problem to date with using the drain and refill on an older transmission and I typically would keep 6 months to a year between drains and refills. There are a lot of examples of transmissions working OK until they are flushed. Essentially if you flush an old transmission you should do a series of flushes to try to remove contaminants before they kill the transmission.
 
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The question of the thread is flush vs drain/refill. While the reasoning may be differ on interpreting the evidence regarding contaminants, the evidence still points to a drain/refill approach.
 
Originally Posted by T-Stick
Jim D. Stokes, manager of technical services for Pennzoil, a leading supplier of ATF, issued a service bulletin advising shops about the risk. Included with the advisory is this sample waiver:

Waiver and Release Automatic Transmission Service

We strongly recommend that automatic transmission service should not be performed on any vehicle that has not had its automatic transmission serviced within the last 60,000 miles. We will perform automatic transmission service on such vehicles at the customer's request only if this waiver and release is signed by the customer:



And of course a problem with signing such a waiver is what if the shop does something stupid and destroys the transmission in a manner unrelated to the actual fluid. Plenty of shops have ruined transmissions such as by removing the wrong bolt, thinking it's a fill plug, and then when the transmission is broken immediately after the fluid change they blame it on the new fluid instead of on the shop being stupid.
 
D&F is only better in people's beliefs. Sonnax studied this extensively and found that even with a D&F, contaminant levels rise hilariously above even pre-change levels shortly after doing a D&F.

Doing a D&F over a flush is good for the spirit, but nothing else.
 
Originally Posted by DoubleWasp
D&F is only better in people's beliefs. Sonnax studied this extensively and found that even with a D&F, contaminant levels rise hilariously above even pre-change levels shortly after doing a D&F.

Doing a D&F over a flush is good for the spirit, but nothing else.

I'd love to hear the science behind that Sonnax statement .
 
Originally Posted by DoubleWasp
D&F is only better in people's beliefs. Sonnax studied this extensively and found that even with a D&F, contaminant levels rise hilariously above even pre-change levels shortly after doing a D&F.

Doing a D&F over a flush is good for the spirit, but nothing else.



https://www.bobistheoilguy.com/foru...-lv-14-684mi-fordfusion-6f35#Post4766692

This contradicts your referenced "study".
 
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