Drain/refill vs diy flush?

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Originally Posted by dave1251
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".


404 Error - Particle Count Not Found

Besides, that appears to be a well maintained transmission that receives regular fluid changes. Same result. Neither service would place the transmission under undue stress when done frequently.
 
Originally Posted by Kjmack
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 .


Gonna quote Greg from Sonnax for about the billionth time on this forum:

Quote
. "When fresh oil is introduced during a service or repair, a fresh load of detergents will pick older settled/compacted particles up and circulate them throughout the system. I have tested and verified this effect in my shop. In a normal working transmission that has never seen a failure with 100K miles, The old/original oil tested relatively clean, the new oil tested clean, 90% of the old oil was changed via drain and fill without pulling the pan. Follow up tests after 10 miles, 80 miles, and 200 miles showed the particulate matter in the oil steadily rising confirming the old concern of servicing older transmissions. In this case the transmission is now running with a greater amount of particulate circulating with the new oil than it was with the old oil.

Gregg continues: "Based on my experiences here, my recommendations for servicing older transmissions that have not had regular maintenance is as follows. Assuming a �normal� service interval of once a year for a vehicle that has never or rarely had a transmission service:
1. Change the fluid and/or filter by any method.
Add a drain plug
2. Relatively soon afterwards, drain the fluid and replace with new fluid. Leave the filter alone.
3. Thereafter, adopt an accelerated service interval by performing drain and fill of transmission fluid whenever changing engine oil (or every other depending on frequency).
4. After a few drain and fill services, return to the �normal� service interval of once a year.

Gregg notes: "Obviously this is not practical for many customers and difficult to manage in the real world. The main point here is not the specific time, or intervals, rather if you truly want clean fluid you will need to also change out the �new� fluid added to older transmissions as it will quickly pick up the old grit that was laying around inside and the only way to get rid of this is to swap the fluid out."


Cliff's Notes: D+F is not doing anything differently
 
Originally Posted by dave1251
You can regurgitate this quote another 200 times UOA's don't bear out the testimony of a transmission shop owner.


Right, because sonnax just such a backwoods mom-and-pop institution.

You have UOAs showing that D+F results in less contaminant build than a full flush? Please post them. Eager to see the UOA comparison between the two.
 
Originally Posted by DoubleWasp
Originally Posted by dave1251
You can regurgitate this quote another 200 times UOA's don't bear out the testimony of a transmission shop owner.


Right, because sonnax just such a backwoods mom-and-pop institution.

You have UOAs showing that D+F results in less contaminant build than a full flush? Please post them. Eager to see the UOA comparison between the two.



You can read I assume? In this post UOA's show wear metals and acids decreasing with less silicates. Therefore the huey of your transmission shop owner post invalid.
 
Can you? I'm not seeing a particle count. Silicates, metals, and acids are not the only contaminants a transmission can contain. Or do you intend to dispute the validity of a particle count entirely?

I see you are still not understanding that Greg Nader is the Product Manager for the Sonnax brand. He's not some bumpkin shop owner talking some bull.

You have shown nothing at all that disputes my assertion that a D+F is exactly no better than a complete flush because you have posted exactly no comparison between the two at all.

You have one UOA of a frequently dumped transmission, when frequently dumped transmissions were never even a topic where flushes of any type were concerned. The big question has surrounded transmissions that were NOT frequently serviced. OP posted about a transmission with 90k on the original fluid. So a UOA about a transmission that's going an entire 15k on it's latest of multiple flushes is about as relevant to this topic at cat memes.

His article also clearly states (if you had read it) that it's about transmissions that have not had regular service. That alone makes the UOA that you keep regurgitating worthless to the OP's situation, and the article.

But go ahead and just sidestep all of that so you can point to that same UOA and make no other attempt at a point at all.
 
Doublewasp,

Assuming a neglected transmission, do you have any opinion that the fluid exchange machine (not "pressurized", as some keep repeating) combined with nearly 100% new fluid could knock off larger chunks of clog potential debris vs. the drain and fill method?

This is the only reason I could possibly imagine that repeated drain and fills might be better than a 100% exchange. Obviously, the Sonnax link does not think there is a difference in the two methods. Maybe the "large chunk" hypothesis is not viable??
 
Originally Posted by DoubleWasp
Can you? I'm not seeing a particle count. Silicates, metals, and acids are not the only contaminants a transmission can contain. Or do you intend to dispute the validity of a particle count entirely?

I see you are still not understanding that Greg Nader is the Product Manager for the Sonnax brand. He's not some bumpkin shop owner talking some bull.

You have shown nothing at all that disputes my assertion that a D+F is exactly no better than a complete flush because you have posted exactly no comparison between the two at all.

You have one UOA of a frequently dumped transmission, when frequently dumped transmissions were never even a topic where flushes of any type were concerned. The big question has surrounded transmissions that were NOT frequently serviced. OP posted about a transmission with 90k on the original fluid. So a UOA about a transmission that's going an entire 15k on it's latest of multiple flushes is about as relevant to this topic at cat memes.

His article also clearly states (if you had read it) that it's about transmissions that have not had regular service. That alone makes the UOA that you keep regurgitating worthless to the OP's situation, and the article.

But go ahead and just sidestep all of that so you can point to that same UOA and make no other attempt at a point at all.

You have made no counterpoint at all. The only thing you have done is quote the same guy who presented 0 data and in the quote provide he stated containments increased with drain and fills. Please provide something other than a profit shill.
 
Originally Posted by dave1251
Originally Posted by DoubleWasp
Can you? I'm not seeing a particle count. Silicates, metals, and acids are not the only contaminants a transmission can contain. Or do you intend to dispute the validity of a particle count entirely?

I see you are still not understanding that Greg Nader is the Product Manager for the Sonnax brand. He's not some bumpkin shop owner talking some bull.

You have shown nothing at all that disputes my assertion that a D+F is exactly no better than a complete flush because you have posted exactly no comparison between the two at all.

You have one UOA of a frequently dumped transmission, when frequently dumped transmissions were never even a topic where flushes of any type were concerned. The big question has surrounded transmissions that were NOT frequently serviced. OP posted about a transmission with 90k on the original fluid. So a UOA about a transmission that's going an entire 15k on it's latest of multiple flushes is about as relevant to this topic at cat memes.

His article also clearly states (if you had read it) that it's about transmissions that have not had regular service. That alone makes the UOA that you keep regurgitating worthless to the OP's situation, and the article.

But go ahead and just sidestep all of that so you can point to that same UOA and make no other attempt at a point at all.

You have made no counterpoint at all. The only thing you have done is quote the same guy who presented 0 data and in the quote provide he stated containments increased with drain and fills. Please provide something other than a profit shill.


You have made no counterpoint at all.

You posted a UOA that has nothing to do with transmissions that don't receive regular service. According to even the most conservative recommendation, that transmission is being serviced FOUR TIMES as frequently as recommended.

Your information is not even at profit shill level. It's 100% irrelevant.

Not that there is any profit shilling going on. Sonnax doesn't make money selling transmission fluid. So how exactly are they lining their pockets off of increasing fluid service.

They make more money by saying nothing at letting transmissions blow so they can sell people parts (which they actually do make money selling)
 
Originally Posted by dave1251
Originally Posted by DoubleWasp
Can you? I'm not seeing a particle count. Silicates, metals, and acids are not the only contaminants a transmission can contain. Or do you intend to dispute the validity of a particle count entirely?

I see you are still not understanding that Greg Nader is the Product Manager for the Sonnax brand. He's not some bumpkin shop owner talking some bull.

You have shown nothing at all that disputes my assertion that a D+F is exactly no better than a complete flush because you have posted exactly no comparison between the two at all.

You have one UOA of a frequently dumped transmission, when frequently dumped transmissions were never even a topic where flushes of any type were concerned. The big question has surrounded transmissions that were NOT frequently serviced. OP posted about a transmission with 90k on the original fluid. So a UOA about a transmission that's going an entire 15k on it's latest of multiple flushes is about as relevant to this topic at cat memes.

His article also clearly states (if you had read it) that it's about transmissions that have not had regular service. That alone makes the UOA that you keep regurgitating worthless to the OP's situation, and the article.

But go ahead and just sidestep all of that so you can point to that same UOA and make no other attempt at a point at all.

You have made no counterpoint at all. The only thing you have done is quote the same guy who presented 0 data and in the quote provide he stated containments increased with drain and fills. Please provide something other than a profit shill.


Let's get something straight here: As of this post, you have supplied absolutely positively no technical data on the effects of introduction of new fluid into a transmission that hasn't seen regular maintenance.

YOU have made no counterpoint at all.

You posted a UOA that has nothing to do with transmissions that don't receive regular service. According to even the most conservative recommendation, that transmission is being serviced FOUR TIMES as frequently as recommended.

Your information is not even at profit shill level. It's 100% irrelevant.

Not that there is any profit shilling going on. Sonnax doesn't make money selling transmission fluid. So how exactly are they lining their pockets off of increasing fluid service?

They make more money by saying nothing at letting transmissions blow so they can sell people parts (which they actually do make money selling)

First he's just a transmission shop owner, now he is just a shill. Keep trying to find excuses for the fact you have nothing to support D+F over a complete exchange. I'm going to keep coming back.

Originally Posted by doitmyself
Doublewasp,

Assuming a neglected transmission, do you have any opinion that the fluid exchange machine (not "pressurized", as some keep repeating) combined with nearly 100% new fluid could knock off larger chunks of clog potential debris vs. the drain and fill method?

This is the only reason I could possibly imagine that repeated drain and fills might be better than a 100% exchange. Obviously, the Sonnax link does not think there is a difference in the two methods. Maybe the "large chunk" hypothesis is not viable??


In every argument for drain and fill where an advantage is going to be claimed, you're going to find one thing every single time:

ZERO technical data establishing superiority

I'd like to see any technical data proving that transmission fluid is some kind of rheostat where I can adjust how much material an old tranny is going to dump.

Quite frankly, I'm not even sure what all of the hoopla is over the "pressure machines" anyway. Unless fluid is forced backwards against the natural flow of the transmission, the "pressurized" fluid is going into the transmission pan. The pan or reservoir is ultimately vented to the atmosphere (because transmission fluid expands and contracts), so the transmission is never going to be "pressurized" anywhere from a "pressure" flush.
 
Originally Posted by JeffKeryk
Drain and fills rock. Honda recommends 'em.
They have worked well for me for many years.


There's also a lot of people out there who Honda automatic transmissions didn't work for.

But that's besides the point. D+F is not a bad thing. It's just no better than anything else out there.
 
Originally Posted by DoubleWasp
Originally Posted by JeffKeryk
Drain and fills rock. Honda recommends 'em.
They have worked well for me for many years.


There's also a lot of people out there who Honda automatic transmissions didn't work for.

But that's besides the point. D+F is not a bad thing. It's just no better than anything else out there.

Seems to me, on something that is frequently getting D&F I could see this being fine. Particulates aren't falling out of suspension, and the fluid is never wearing out fully, and is getting various additives refreshed. It's probably "good enough".

But if the fluid is run to the end of its life (or beyond), that would be a different story. Sonnax's story about new fluid getting just as dirty as old is interesting. Sounds like, on a really neglected transmission, multiple flushes might be needed to truly clean it up. [Of course, just how clean does it need to be? different question altogether.]
 
Originally Posted by supton

Sonnax's story about new fluid getting just as dirty as old is interesting. Sounds like, on a really neglected transmission, multiple flushes might be needed to truly clean it up. [Of course, just how clean does it need to be? different question altogether.]

It kind of looks like DoubleWasp and some others are arguing with each other about different things.
Or perhaps just partially irrelevant things.
Or just imo a main point is being lost in the process.

DoubleWasp says D+F is no better (and probably worse?) than a full flush.
He quoted Greg from Sonnax as evidence.

Greg from Sonnax said on a 100,000 mile vehicle with the original trans fluid, replacing that fluid with 90% new fluid caused particulates to increase soon after.
Greg from Sonnax recommends on a neglected vehicle to change the trans fluid by any method multiple times.
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.

Cliff's Notes: D+F is not doing anything differently

If it exists, I missed seeing direct evidence showing whether a D+F or full flush increases more particulates than the other.
I would expect particulates to rise on a neglected transmission soon after doing a D+F.
Logic tells me replacing 30% of the fluid will free up fewer particulates and at a slower rate than replacing 100% of the fluid would.

But that's the partially irrelevant part.
Because if the person is trying to catch up on maintenance for their neglected transmission, then both D+F and a full flush should be repeated again fairly soon anyway, since both methods are increasing particulates.

In general, I'd say what Greg from Sonnax said actually favors the typical D+F method since people who do D+F on a neglected transmission tend to do it multiple times in a short timeframe. (Arguably too short if done again in less than 100 miles.) Most people who do a full flush apparently tend do it once and call it good since they replaced all of the old fluid with new fluid.

So, if done multiple times, D+F is probably better than a full flush done once. A full flush done multiple times is probably better than D+F done multiple times. The usual argument can be made that D+F causes less particulates shock to the transmission since 30% new fluid logically doesn't clean as fast as 100% new fluid. But, in either case, the main thing is that particulates freed up by a D+F or by a full flush need to be drained out again anyway in the not too distant future on a neglected transmission. I just thought that point was being lost.
 
Originally Posted by Back40
Why would replacing 1/2 the ATF be preferable over a low pressure flush?


Original Post posed a question which there are many opinions on. There is no right answer. Circumstances vary. Although I am skeptical of what some people believe to be fact. They can continue to hold onto their beliefs. I will follow my own course.

My own opinion is that replacing only half the fluid is not preferable over a complete fluid exchange. Drain & fill 3 or 4 times, and you will have almost 100% fresh fluid. Drain the transmission from the return line until clean fluid is coming out, and you will have almost 100% fresh fluid. Fresh fluid is always preferable to mixing old & new fluid. Yes, fresh fluid with it's fresh additive package and fresh detergents, will clean off some of the build-up which the contaminated fluid was not removing. So now your fresh fluid is working, there are more contaminants in the fluid. Would you rather have those contaminants still stuck in your transmission's moving parts? What you need to do now is change the fluid again. Drain out the contaminants which your fresh fluid cleaned off the transmission. Now you will have clean fluid with a clean transmission. Or would you rather have contaminated fluid with sludge, varnish, and metal floating around?

Imagine a cup. You drink everything from that cup. You never wash it. You pour the next beverage into it, while a little of the last drink is still in the bottom. Coffee, tea, hot chocolate, beer, milk, juice, soda.......the inside of that cup will have everything stuck to it. Then suddenly, some soapy water got in. All that stuff stuck to the side of the cup is free, and now floating around in the cup. Do you continue to drink from that cup? Do you add the next refreshment in with that soapy water, and all the crud swilling around? Or do you actually wash it out before you drink from it again?

On another forum, a member plans to drain his transmission pan from the drain plug. Add 3 quarts of fresh fluid. Fill those empty bottles with contaminated fluid. Then however much contaminated fluid is left over, he will pour back into the transmission. His belief is that this method will provide a true level of transmission fluid fill, since the transmission does not have a dipstick. He could also measure the amount drained, and refill with the same amount. The transmission also has a fill plug on the side. Run the engine until the transmission is at operating temperature, open the fill plug, add transmission fluid until it reaches the fill plug level. But this guy is going to pour 1.25 quart of contaminated fluid back into the transmission, right into the 3 quarts of fresh fluid.

The transmission in question calls for a 4 liter fill, it's in the owners manual.. This transmission is serviced by draining and filling 3 times, as per the service manual. I do the triple drain & fill, and fill with 4 liters.
 
FWIW: On a minivan I once owned, did the recommended machine flush (FireStone store) where they put cleaners into the fluid first (I would imagine to bust loose the grit/dirt/debris) then replace with fresh fluid using the flushing machine (BG?). The transmission failed in a couple of weeks (went from no issues at all) and had to be rebuilt.

After that I tend to do the simple OEM method of a drain/fill every ~30K miles but WITH a Magnafine transmission filter in the return line as well on my Optima.
At my last drain/fill, I did it twice within 25 miles (got the ATF hot by highway driving) and replaced the Magnafine filter to boot.

At my first 30K drain/fill, the OEM ATF was black and nasty (added Magnafine filter at initial 8K point). At my second 30K drain/fill, the OEM ATF was still nice and red and the filter (I took it apart) had some metal "mush" on the magnet but the filter media "looked" clean to my eye.
 
Last edited:
Originally Posted by WhizkidTN
FWIW: On a minivan I once owned, did the recommended machine flush (FireStone store) where they put cleaners into the fluid first (I would imagine to bust loose the grit/dirt/debris) then replace with fresh fluid using the flushing machine (BG?). The transmission failed in a couple of weeks (went from no issues at all) and had to be rebuilt. .



That was a big problem with those types of "transmission flush". The machine actually used pressure and chemicals to flush the inside of the transmission. On some cars, the pressure actually loosened or broke parts in the transmission. On some cars, the chemicals created problems since the transmission was never engineered for harsh solvents.

In the modern world, the transmission service machines no longer do that. The machine connects to the transmission at the cooling and return lines. The vehicle is turned on. The transmission's pump pushed fluid out the cooling line, as it normally does. The contaminated fluid goes into the machine. Fresh fluid in the machine is returned to the transmission. No pressure. No flushing. No extra chemicals added. No damage to the transmission.
 
Originally Posted by DoubleWasp
Originally Posted by dave1251
Originally Posted by DoubleWasp
Can you? I'm not seeing a particle count. Silicates, metals, and acids are not the only contaminants a transmission can contain. Or do you intend to dispute the validity of a particle count entirely?

I see you are still not understanding that Greg Nader is the Product Manager for the Sonnax brand. He's not some bumpkin shop owner talking some bull.

You have shown nothing at all that disputes my assertion that a D+F is exactly no better than a complete flush because you have posted exactly no comparison between the two at all.

You have one UOA of a frequently dumped transmission, when frequently dumped transmissions were never even a topic where flushes of any type were concerned. The big question has surrounded transmissions that were NOT frequently serviced. OP posted about a transmission with 90k on the original fluid. So a UOA about a transmission that's going an entire 15k on it's latest of multiple flushes is about as relevant to this topic at cat memes.

His article also clearly states (if you had read it) that it's about transmissions that have not had regular service. That alone makes the UOA that you keep regurgitating worthless to the OP's situation, and the article.

But go ahead and just sidestep all of that so you can point to that same UOA and make no other attempt at a point at all.

You have made no counterpoint at all. The only thing you have done is quote the same guy who presented 0 data and in the quote provide he stated containments increased with drain and fills. Please provide something other than a profit shill.


Let's get something straight here: As of this post, you have supplied absolutely positively no technical data on the effects of introduction of new fluid into a transmission that hasn't seen regular maintenance.

YOU have made no counterpoint at all.

You posted a UOA that has nothing to do with transmissions that don't receive regular service. According to even the most conservative recommendation, that transmission is being serviced FOUR TIMES as frequently as recommended.

Your information is not even at profit shill level. It's 100% irrelevant.

Not that there is any profit shilling going on. Sonnax doesn't make money selling transmission fluid. So how exactly are they lining their pockets off of increasing fluid service?

They make more money by saying nothing at letting transmissions blow so they can sell people parts (which they actually do make money selling)

First he's just a transmission shop owner, now he is just a shill. Keep trying to find excuses for the fact you have nothing to support D+F over a complete exchange. I'm going to keep coming back.

Originally Posted by doitmyself
Doublewasp,

Assuming a neglected transmission, do you have any opinion that the fluid exchange machine (not "pressurized", as some keep repeating) combined with nearly 100% new fluid could knock off larger chunks of clog potential debris vs. the drain and fill method?

This is the only reason I could possibly imagine that repeated drain and fills might be better than a 100% exchange. Obviously, the Sonnax link does not think there is a difference in the two methods. Maybe the "large chunk" hypothesis is not viable??


In every argument for drain and fill where an advantage is going to be claimed, you're going to find one thing every single time:

ZERO technical data establishing superiority

I'd like to see any technical data proving that transmission fluid is some kind of rheostat where I can adjust how much material an old tranny is going to dump.

Quite frankly, I'm not even sure what all of the hoopla is over the "pressure machines" anyway. Unless fluid is forced backwards against the natural flow of the transmission, the "pressurized" fluid is going into the transmission pan. The pan or reservoir is ultimately vented to the atmosphere (because transmission fluid expands and contracts), so the transmission is never going to be "pressurized" anywhere from a "pressure" flush.



I feel bad for you as you are unaware you can not provide anything but a quote no data nothing it must be hard to live life without a clue.
 
When I bought my '04 Corolla it had 148K miles and I had no idea if the tranny fluid had ever been changed. Because of this, I decided to do drains and fills every oil change (the first time I dropped the pan and changed the filter). I did this every oil change for about 3 times, then I went to every other oil change for about another 3 times, and now I do a drain and fill every 24K miles. The reason I decided to do this was solely because I had no idea of the condition of the fluid that was in it when I bought it, and I had no idea if the fluid had ever been changed. I didn't want to do a flush and have sludge dislodged and then end up somewhere else in the tranny causing problems. The car now has 375K miles and is still on the original tranny, so I guess this method works...
 
Originally Posted by grampi
When I bought my '04 Corolla it had 148K miles and I had no idea if the tranny fluid had ever been changed.


What color was the fluid when you bought it and which atf do you use in it? Thanks!
 
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