Drain/refill vs diy flush?

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I am an advocate for the fluid exchange using the return cooling line. If you have a thermal bypass valve, you may need to remove it. I have done this method with great success in my Tb, old 2011 Ram 1500, 1993 C1500 and my brother in laws 1995 Jeep YJ, TJ, or what ever designation they were using for that year. The Jeep used some sort of Aisin 3 speed if I recall and the pump only engaged when you shifted to neutral or driving gears.
 
Drain and fill is popular, esp when the manufacturer gives you a drain plug.

I drain and fill the 2010 accent aprox. yearly. Fluid never gets cruddy, I'm fine with replacing 1/2 capacity yearly.
Takes about 5min.. less if I do it at same time as oil change.

Hyundai SPIII 7$/qt from the dealer.

Also: there is no serviceable transmission filter on these, just a rockcatcher screen.
 
What is a flush

Should I flush my trans? (get rid of the old fluid and put new in)

Or drain and refill my trans? (get the old fluid out and put new in)


Couple drain and fills will get you to a new fluid state. Don't overthink it. And don't go fussing with all that nonsense about pulling the cooler lines off and turning the car on. That puts you at a good risk of running your oil pump dry.
 
Originally Posted by Sayjac
I was under the impression that most of what passes for a complete shop "flush" these days, is basically a trans return line exchange of all fluid. The difference, done with a machine rather than passive diy. I think the biggest issue folks like Honda have with ATF "flush", is when chemicals are added to the process. Then it becomes a
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My .02

I thought that Honda's preferred method these days is to do 4 consecutive drain and fills at about 100k miles/10 years and driving around around the block between fills. For something like that I might consider just reusing the crush washer each time. until the final refill.

Back in the day they just recommended a single drain and fill every 30k miles. I understand that a lot of people just do that. I dealing with a rebuilt transmission and I'm not sure if it's worth doing an early drain and fill. I thought that it's not much different than a new transmission, which they don't recommend getting a drain and fill until about 100k miles.
 
Have always done drain/fill...but with initial change with filter around that 30-40k mark. Then 30k d/f after that. Have the same Rav4 as OP...trans capacity is listed 6.9 qt, drain with filter is right around 4qt, and drain without filter is 2.5 qt. This is the wife's grocery getter so fairly easy service. Have considered an exchange...especially for my Tundra that I tow with frequently, but these 30k d/f seem to keep the fluid clean enough and so far without issues.
 
Originally Posted by SnowDrifter
What is a flush

Should I flush my trans? (get rid of the old fluid and put new in)

Or drain and refill my trans? (get the old fluid out and put new in)


Couple drain and fills will get you to a new fluid state. Don't overthink it. And don't go fussing with all that nonsense about pulling the cooler lines off and turning the car on. That puts you at a good risk of running your oil pump dry.


Far from nonsense, the only thing you get is diluted dirty fluid. Some manufacturers spec line off exchange in the FSM as the preferred way to change the fluid, do it right and there is no chance of damaging the pump.
 
My AS69RC requires a drain and fill every 48,000km and filter at 96,000, although it is based of the most severe commercial use. They were kind enough to give us a drain plug though....
 
Originally Posted by DGXR
If you plan to keep the vehicle long-term, it's a good idea to drop the pan at least once and see what is going on on there... replace the filter and gasket. I would guess the reason some people prefer the drain & fill method over the return line "flush" method is because it's just easier, and perhaps less messy. I dropped the pan once on my 2006 Tacoma at 120k miles, cleaned the magnets, replaced the filter & gasket -- there was hardly any buildup at all on the magnets and everything looked great. Based on this (and how I use this truck), there is no reason to drop it again. Doing drain & fills every 30-40k from here forward.

You can't "see" depletion of additives so I would think a wise schedule would be dependent on usage & load.
 
I prefer to call fluid exchanges "flushes" as it brings out all those who are anti-flushing... Even though I consider it similar to what happens in the water closet.

I get the idea of doing it with a drain and fill, but IMO drain&fill only makes sense if you are changing "mostly good" fluid. Then you are taking fluid at 50% life, mixing with 100% life fluid, and have something that is between those limits--in other words, far from shot. Far from worn out, loaded up with clutch material, whatever the metric may be.

If the fluid looks to be end of life, why not just change it all at once? Less fluid wasted, and then you can do drain&fill if you want.
 
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).
 
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.
 
Originally Posted by BrianF
They were kind enough to give us a drain plug though....


Luckily with both my Hondas, this is the case..
I got on a D&F bandwagon after i realized I had neglected the TL on trans maintenance.
So I did a 3 x D&F to begin with on both vehicles.
Now its a 1 x D&F every spring.. its easy, and i have peace of mind..
J.
 
Originally Posted by y_p_w
…..I thought that Honda's preferred method these days is to do 4 consecutive drain and fills at about 100k miles/10 years and driving around around the block between fills.
I've seen 3x times d&f method noted as a way to get majority of old out and new in. I suppose 4x would give an extra measure of "safety". The actual procedure for doing it with a lift is documented in this link. I love the reference to "Acura Precision Crafted ATF-Z1" That's comedy gold right there. I would bet that if a dealer did that procedure, the price would be astronomical. And that most do simple single d&fs.

Personally I've never done anything but single d&fs at 25-35k miles on a couple Honda applications that are noted to be either failure prone or tough on ATF, 01 Civic an 3.0L V6. Both with original trans and using MaxLife since Z1 discontinued. The former with ~300k miles now.

All that said, main point was/is that imo Honda's main issue with machine "flush" procedure is possibility that outside of use of ATF, cleaning chemicals/agents are or could be introduced in the process. Then it would become a no go.
 
#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
 
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.
 
Originally Posted by Donald
Originally Posted by BMWTurboDzl
IIRC the general argument(s) against a flush are:
#1 Dislodges crude in a neglected transmission which causes a failure.
#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.
#3 Flush is performed using excessive pressure.
#4 Flush has never been proven to extend the life of a transmission and instead just increases the risk of introducing contaminants into the unit.

Again these are general arguments and some may/may not apply to your particular transmission.

Where did you come up with this load of crap?

Do you know how a flush or total fluid exchange is performed? It uses the pump in the transmission to push the new ATF through the transmission just like it does when you are driving. The flush machine only refills the pan with new ATF at the same rate that the transmission pump pushes old fluid out. There is no high pressure involved. However you introduce new ATF will clean the transmission of sludge and contaminants which is what you want. If a total fluid exchange causes any transmission issues the transmission was on its way out.


Have to agree with this. Just had a Subaru full pan drop and using lines to fill/flush system and it shifts without the clunk it used to have and the torque bind has now officially disappeared. Get the fluid out regularly. It's a good thing.
 
Doing a transmission fluid drain and fill does not waste good ATF. It exchanges some old fluid for some fresh fluid. This boosts the lubricity, detergency, and other qualities of the fluid to maintain smooth, efficient and reliable operation of the transmission. While it is true that a total transmission fluid exchange is a better overall service, this does not mean that a drain & fill is pointless. For this this PM service, have already dropped the pan to replace the filter & gasket, so going forward I prefer to do a periodic drain & fill than to disconnect fluid lines and run the vehicle while trying to pour in transmission fluid at the same time.
 
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.



+1
 
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