"Partial" ATF change?

tqh

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My friend/mechanic recommends me doing a "partial" ATF change, i.e. without pumping out all old fluid, hence maybe half or a third of the old fluid in the transmission would stay and be mixed with the new fluid. He himself do this to his car every 30K miles. Is it good/bad, what do you think? (Car: Camry 2009)
 
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Regularly done, its much safer than the "power flush" that some service centers hawk. On cars without a convertor drain plug, its the only option other than a power flush.
 
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Originally Posted By: tqh
My friend/mechanic recommends me doing a "partial" ATF change, i.e. without pumping out all old fluid, hence maybe half or a third of the old fluid in the transmission would stay and be mixed with the new fluid. He himself do this to his car every 30K miles. Is it good/bad, what do you think? (Car: Camry 2009)
Good idea, how much will he be charging if you don't mind me asking? I hope he's planning on using the Toyota WS fluid in there. That car may have a sealed transmission so I hope he knows how to do it correctly. Maybe stand there and watch him to make sure the service is actually done. My dad's 07 Camry I4 went 80k on the FF. Fluid was still pink/red. It's a long life fluid. The atf dipstick went away in 09- or 2010. So maybe only do this if you're planning on keeping the car for the long haul.
 
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tqh

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He is going to teach me how to do it myself... I don't know whether it's safe for the tranny.
 
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A typical drain and fill will likely exchange about that much. I don't even run a full flush unless I'm dropping the pan to change the ATF filter. Some newer transmissions without the dipstick have an upper ATF fill hole (similar to MT or differentials) to check the fluid level. You need a SST (merely an aluminum key bent at 90 degrees) to check from the fill hole.
 
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Perfectly safe for the trans. The only concern is that you should do it more often than you would if a full drain were possible (as it is in older cars with convertor drain plugs). Just pulling numbers out of my ear, a partial change every 60k is just as good as a full change every 100k miles.
 
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Your friend is wise. Since over half of the ATF resides in the torque converter, regular changes of what fluid is in the pan will keep all the ATF in good shape. Since most Japanese automatic transmissions have a drain plug, changing the fluid in the pan is pretty easy, kind of like changing oil. I would recommend popping the drain plug on the auto trans every 30K max and refilling.
 

tqh

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Thanks all! It sounds great. It's an I4 2009 and has a dipstick to check ATF fluid.
 
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By partial change if you mean drain and fill with Toyota OEM ATF, than yes that is what I would do. I have had it done once. Drain and fill essentially. I would do it every 60k miles not every 30k miles. Not necessary, fluid in my 2007 is considered lifetime unless under extreme conditions. I figure every 60k miles is more than ok.
 
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My understanding is that the most important reason to perform a partial change is that the additives break down. A partial change restores these additives. If it were so important that changes be performed to drain out the majority of the transmission fluid, they would be designed to do just that. Now I wonder why there aren't more transmission that use spin on filters. I remember the odd thing about OEM Subaru oil filters is that they say "ENGINE" on them. And the reason why is because there is a separate OEM filter that says "TRANSMISSION". Now the odd thing was for some reason I saw an application guide (might have been for my WRX) and the filter specified by that company (Wix?) for the transmission was actually an engine oil filter. I heard that Subaru doesn't actually specify a filter change interval, but a lot of people do it anyways when they change the tranny fluid.
 
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Lifetime....of what the fluid...the transmission...the warranty...it is never lifetime. I have never had a transmission problem on any car that I have owned...fluid is always looking fresh, performance is as new. My Suburban tows regularly and its doing great. Its best to have a most fresh baseline to start from though. ATF is cheap, do 1-3 partials then every year from there. I have found that regular dino ATF changes is more effective than a single extended drain synthetic ATF change. Yearly partial drain/fill is the caramilk secret...for transmissions.
 
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This is a sound method, particularly for those trannies lacking a serviceable filter. Quantity should be no problem. Just fill up with the same volume you drained out.
 
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Each time i do a engine oil change,i also pull the torque converter drain plug witch result in the transmission giving up 2.5 quarts.I then refill with full synthetic dexron6.The 2005 Malibu should be mostly changed from dexron3 to dexron6 in another 18 months.
 
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I drain my transmission pan when I do engine oil changes. I already have the tools out, car up, drain pan on the floor, etc., so it only takes an extra few minutes. On my 4L60E deep pan trans, I get about 4-5 quarts out. I drop the pan and change the filter every 50k miles. I run Valvoline Maxlife Dex/Merc.
 
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