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The lovely Automatic Transmission fluid, always a pain. The question is to flush or not to flush? I’ve heard people (including some mechanics) claim that transmission flushes will screw up your transmission and just generally cause trouble, yet there are still many shops that still offer this service.
What is everyone’s opinion on this? Is flushing neccessary? Will it ruin your transmission, or is it safer just to change the fluid?
or does it all depend on the situation?
Thanks in advance
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I’ve heard people who say that you shouldn’t change engine oil at all, cause it’s better for the car. The world is full of this kind of people 🙂
In my opinion every oil or fluid should be changed, because it wears out.
Mercedes Benz and Volvo had a ‘sealed for life’ policy about their A/T. But it backfired at them. Now Mecedes recommends fluid flush even after 60.000km.
From my experience I can tell – Volvo Transmissions without any flui changes die after 150-180k km, a well maintained Volvo transmission with 60.000km fluid change lives up to 500-600k kmThanks for the reply. I knew that changing the fluids is definitely important. My question was more in reference to flushing the transmission fluids. I’ve read many people say that they do not recommend flushing the transmission fluid, because the machine use to flush it could cause transmission problems. These people recomend instead draining the transmission fluid, and adding the appropriate amount of new fluid.
What are your thoughts on that? Is flushing a safe method used to change transmission fluid?
As long as the transmission doesn’t run dry it should be OK.
The most popular method is to drain the transmission, replace the filter(if it has one), refill with the amount you drained and then flush the rest disconnecting the return hose from the A/T oil cooler and pouring fresh fluid. IMPORTANT NOT TO OVERFILL ! There are tons of videos about flushing AT on YouTube.
I never flushed a transmission using the special flushing machine, so can’t say anything about that method.The flush ruining the transmission is pretty much a myth if done correctly. The pan should be dropped, cleaned, and the filter replaced. Then the flush is done.
I’ve heard the phrase that the high pressure of a flush machine is what kills the transmission. Most flush machines use the pump that is inside the transmission to flush the system so excess pressure is not an issue.
If the transmission fluid hasn’t been changed in a really, really long time (100k+ mi) it is probably safer to do a series of drain and refills over a few months. From what I understand, it’s not so much the flushing that causes problems, but introducing brand new fluid all at once. It’s like if you ween it off the really old fluid, there’s less likely to be an issue. I don’t know why but this is just what I’ve seen.
I am of the opinion that on lower mileage cars 75k and under that a flush is ok. IMO on higher mileage vehicles of questionable service history, I think a fluid and filter change is the way to go.
I have a 2007 Odyssey. I was at the honda dealer for some recall service and he saw the transmission code on my maintenance minder and asked if I wanted my transmission serviced. I told him I was doing it myself. He said whatever I do, do not have the transmission flushed because the the contaminants could get loose and damage the transmission. He said just do a simple drain and refill.
from everything i’ve ever been told by mechanics and tranny shop techs, i’d have to agree with sigsaurp228. i’ve always been told that a flush is good if the car is newer but do not flush (only service ie. fluid and filter change) if the car is older because sometimes the gunk that a flush will remove is actually keeping things together. as well, if that gunk is removed or dislodged it can end up re-lodged somewhere else you dont want it.
[quote=”stiv625″ post=118043]If the transmission fluid hasn’t been changed in a really, really long time (100k+ mi) it is probably safer to do a series of drain and refills over a few months. From what I understand, it’s not so much the flushing that causes problems, but introducing brand new fluid all at once. It’s like if you ween it off the really old fluid, there’s less likely to be an issue. I don’t know why but this is just what I’ve seen.[/quote]
If your at all worried about flushing this is the safest way if your prepared to change it alot more regularly until it stays cleaner on it’s own.
With engine oil the only cleaner I’d use on a suspected abused car is a mild long term cleaner like archoil ar2300 that can need as much as 4000miles depending on the engine oil to do it’s thing, not sure if it’s any good for transmissions though. the last think you want is a big lump of gunk in the oil or fluid pumps or anywhere else really impeding the flow of oil or fluid.
Even though this seems to be a rehashed dead tread I am going to state this DO NOT FLUSH. If you look at your manual or call your car manufacturer they will tell you this. As for cleaning out a system for engines do oil changes more frequently along with using a better quality oil though if the engine is past the 50k mark switching to synthetic may cause leaks due to it cleaning away the dam of dirt that was holding back the oil.
For A/T you should not change your oil unless it is during the specified service interval, smells burnt, or has otherwise been contaminated. A/T use friction material in 90% of the cases and that friction material comes off and stays floating in the oil allowing for it to get stuck between what is left and the metal pars of the clutch pack allowing it to grip and shift. When you drain and replace you remove that friction material.
Flushing is bad because it knocks loose dirt and the dirt gets stuck in places it shouldn’t be. Think of plaque inside your veins and heart attacks its the same idea only engines don’t heal themselves.
I do flushes and pain drops almost daily, and this is how I explain it to my costumers. Most transmissions hold 12+ quarts of fluid. If you are just dropping the pan and changing the filter you will probably change around 5 quarts. When i flush if at all posable i will flush more fluid thru than the transmission holds by about 2 quarts or so to get as much of the contaminates out as possible. I also let the transmissions pump do the work of the fluid transfusion, I don’t like to use an auxiliary pump that may produce to much pressure or flow the incorrect way causing transmission damage. Not that being said its not a good practice to flush untying with known transmission issues, or that has a questionable service history because its a service just like an oil change not a repair.
I think those flushing machines that leave the pan are a joke. Your way is better although more labor intensive. I wouldn’t ever do any type of transmission service without completely cleaning the scum off the pan after removal before anything else which is sounds like what you do.
Sometimes it’s near impossible to kill an old wives tale.
There’s nothing wrong with flushing if the pan is dropped, cleaned, and the filter changed before the flush is done.
If a problem surfaces later then it’s more than likely because the transmission had never been serviced before or someone was having it flushed as an attempt to cure a problem.When the trans does die the flush machine becomes the scapegoat.
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