Drain/refill vs diy flush?

[gman2304]

Originally Posted by Reddy45
Originally Posted by alcyon
For me I just dont want the hassle of dropping the pan, and also since I am doing this job alone, there is risk that the trans will run dry for a moment, If I dont off the engine on time. Looking at the pan while its draining, then getting up and getting to the key to turn it off takes a few seconds.
So I just do several drain and fills on a weekly basis (1 time a week for 3 weeks).


Same. I actually just do a single drain and fill every other year and that still keeps the fluid looking fresh.
. X3 only I siphon about 3 quarts from the fill tube then replace with 3 quarts. No mess no fuss and it takes about ten minutes. My pan has never been off my 4L60E and it just rolled over 203,000 miles. Shifts like butta and fluid is nice and red looking. As always YMMV.

 

[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.

 

[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.

 

[HangFire]

Originally Posted by BMWTurboDzl
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.


I think there's a lot of truth to transmission life being linked primarily to design, build quality, and parts quality. But I think there's more to it than that, particularly with some transmission designs. So, I'll add my anecdote.

I'm keeping a Honda Pilot transmission alive right now via 1K mile drain-n-fills. If I don't, I get sensor and solenoid stuck codes. If I do, it operates very well, once warmed up, like nothing is wrong. This transmission is worn-out at 214K miles. The fluid goes very dark with non-magnetic material every 1K miles.

So IMHO some drain and fills at early life and mid-life will help prevent stuck sensors and solenoids later in life. Stuck sensors and solenoids can drive bizarre shifting behavior that can drive down the remaining life of a transmission. This downward spiral is a different causality than design/build/parts quality, and preventable through preventive maintenance. Meanwhile design/build/parts quality is mostly unaffected by preventive maintenance.

 

[stanlee]

Originally Posted by KrisZ
Originally Posted by stanlee
Originally Posted by fireman1073

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.


Your theory and the theory of the old fluid acting as friction aids are both anecdotal HOWEVER I'm not talking about wearing quicker, I'm talking about transmission shifting fine with 200k miles transmission fluid and IMMEDIATELY slipping badly with new fluid. Dirty fluid can cause solenoids to stick and act erratic however changing to new fluid can't possibly worsen the propensity for solenoids to stick.

 

[SteveSRT8]

Originally Posted by BMWTurboDzl
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.



Completely true and spot on. We all have our opinions, but they are seldom based on facts only.

I have a good opinion of fluid exchanges as they seem to perform well for us here in a very heavy duty cycle. I also have performed them on many different cars and trucks with a B&G machine I bought at an auction. Never anything but great results, sometimes amazing.


Some cars will do well, others won't. There is simply too much variation in design and application...

 

[CT8]

Replacing half the fluid reduces the contaminants by approximately 50%.

 

[KrisZ]

I have a bit of experience, not just opinion, although very limited from the hydraulic farm equipment my brother and I repaired after we got tired of the local mechanic charging us for a full pump replacement everytime the hydraulics started to get slow and required excessive RPM to do the work.

I've seen first hand how the sealing surface of the control valve cylinders was scored by metal shavings, which caused excessive leakage. And I'm talking about imperfections that looked like scuff marks for the most part.
After changing the control cylinders and replacing the hydraulic fluid, which was never replaced and the local mechanic never recommended it to be replaced, the hydraulics started to work perfectly even at idle RPM.
That fluid was full of metal shavings from years of usage.

Now for automatic transmission, most of the wear material in the fluid is from clutch pacs, not metal shavings, so the valve sealing surface damage would not be as severe and it stands to reason that the fine, powder like material could aid in sealing some of the leakage.
It certainly is a much more likely possibility than the increase of fluid friction properties due to presence of wear particles.

 

[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/

 

[SilverFusion2010]

I was getting some rough shifting with the fusion. Drain and refilled about 4.5 qt, transmission shifts quick and smooth with no hesitation or jerking.

 

[Asltrfl]

I have a 1985 Chevy Caprice that I drive 50 miles to and from work 5 days a week. It has had a small trans pan gasket leak ever since I've owned it. A very consistent leak, about 2/3 of a quart a month. I've been doing this for 20 years now. I bought it with 67K and now it has 237K. And the 700r4 shifts perfect, and I drive it hard to work 5 days a week (because I'm always late). My wife drives her Tahoe like an old lady, and the trans took a crap at 170k. I checked her fluid level once every few months, smelled it, and checked the color. But never thought about changing trans fluid. Back in the day, all the shade-tree mechanics said no need to change/flush fluid as long as it didn't smell or look burned.

Well, because her trans blew, I started studying transmissions because I'm an engine guy and figured it was time to fix it myself or pay someone through the nose. All I can add is that the 35 year old trans with the constant "drain and fill" seems to work pretty good. Or should I say "leak and fill". And total neglect, even if the fluid smells good and is a nice red color on the dipstick does not work so well.

So I'm going to take a .010 drill, and put holes on all my cars tranny pans from now on, or maybe just leave a few bolts out of the corner of the trans pans. Plus it keeps the driveway lubricated!

 

[T-Stick]

I think the poster was merely stating the reasons which are typically mentioned - whether or not everyone deems them valid. I have heard all those reasons before along with people's testimonials of seemingly fine transmissions taking a crap after a pressurized fluid exchange. Some vehicle service manuals specify drain/refills. I have heard dealership service techs warn against pressurized fluid flushes--especially on higher mileage units that were never changed. Myself, on an older vehicle for the first change, it would be a drain/refill or pumping out the return line while filling with new fluid. I would not recommend any artificial pressure flush on any vehicle for the first time if it has over 100k on the fluid.

 

[BlueOvalFitter]

Why not just drop the pan and drain it only? Bolt it back up and just add the required amount of fluid. Then, next time, replace the filter and add the required amount of fluid.
Isn't that how most people are doing their oil changes today? If it's good enough for the engine, why not the transmission too?

This would be a good time to add a drain plug to the pan. It makes things a lot less messy when removing the pan.

 

[doitmyself]

Originally Posted by T-Stick
I would not recommend any artificial pressure flush on any vehicle for the first time if it has over 100k on the fluid.


I don't think anyone here has ever produced evidence that a pressurized transmission flush machine exists. Even machines that have words "power flush" in their name are still just an exchange unit that uses the tranny pump to move the fluid.

 

[T-Stick]

No matter how it is described there are still a lot of cautions with this approach.

 

[JTK]

Originally Posted by doitmyself
Originally Posted by T-Stick
I would not recommend any artificial pressure flush on any vehicle for the first time if it has over 100k on the fluid.


I don't think anyone here has ever produced evidence that a pressurized transmission flush machine exists. Even machines that have words "power flush" in their name are still just an exchange unit that uses the tranny pump to move the fluid.



Or how about the one that somehow forces ATF backwards through the transmission?

Those twin chambered ATF transfusion machines are the bee's knees for sure. I've never used one, or had one done. Too cheap and I DIY all messy like.

 

[T-Stick]

Older transmissions sometimes benefit from a certain amount of particles in the fluid to aid the clutches' grip. A drain refill occasionally will keep a percentage of particulates and still refresh the fluid. The transmission essentially stays in a more steady state of lubricity. The pressure flush, despite what it purports to do sometimes dislodges dirt from where it was doing no harm and puts it in harms way. So while you can say if everything is working properly a flush won't hurt it--this may be true in the sense of clutches with no wear and transmissions with no deposits. However all clutches will wear and most transmissions will create some deposits. The drain/refill helps preserve an older transmission that is working fine for its age and does not introduce variables that might kill it.

 

[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/

 

[T-Stick]

contaminants and particulates are not always one and the same

 

[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