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I have a 2005 Odyssey with 66,000 on it. I purchased the car used and don't believe the ATF was ever changed. I recently had it to the dealer for a recall. They must have checked the ATF fluid and said it needs changed ASAP. I checked the dipstick myself and it looks awfully dark. Not reddish.

My questions is should I do a total flush or is a dump and refill sufficient? I've read the ATF posts here but can't reach a conclusion. Any thoughts? Thanks in advance.
 

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Since Honda ATF was supposed to be changed at 30K miles, your van is way overdue for a total ATF replacement. This is easy to do.

Get 10 quarts of Honda ATF.
Do a 3 X drain and refill.
Drive around for 10 minutes after each refill.
 

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Discussion Starter #3
Thanks for the advice. I was sorta leaning to a total replacement because of the dark color of the ATF.
 

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Thanks for the advice. I was sorta leaning to a total replacement because of the dark color of the ATF.
You may not understand that you cannot "sorta" do a "total replacement" because the total volume of ATF is about 8.3 quarts and it does not all drain empty when you remove the drain plug.

You can only drain about 3.5 quarts at a time -- the rest remains trapped inside. This means that must you drain and refill and then, in between, run thru the gears to mix up the ATF and then drain and refill again, and again, in order to continue to dilute the old ATF.

Three drains and refills will give you about 81% new ATF; 4 drains and refills about 89% new ATF; 5 drains and refills about 93.5% new ATF; and so on.

There are other posts that describe a procedure wherein you introduce new ATF into a running transmission that is simultaneously draining -- but this is a bit more complicated.
 

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a procedure wherein you introduce new ATF into a running transmission that is simultaneously draining -- but this is a bit more complicated.
Sounds more complicated but I think will end up being much easier and quicker than 4x Drain and Fill.
 

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Just word of warning.

When a transmission has NEVER had its fluid changed it will build up a significant amount of sludge, but the transmission seems to operate fine since the sludge accumulates over time, and hides it crevasses or walls that are not affected by the main flow of fluid ....until you actually change the fluid. One theory is that the new fluid loosens up the built up sludge, and then this sludge gets caught in one or more of the many critical hydraulic channels throughout the the system. This leads to transmission failure, usually within the next 20-40K miles.

One analogy:
Imagine a river of polluted water. Let's use visible pollution like garbage, logs and branches. As these pollutants were added to the river, they found a natural resting area on the river bed, the shoreline, or got stuck on rocks in the middle of the river. None of these pollutants inhibited the flow of the water, because they were slowly added to the system over time, and the areas with the most water flow (such as the middle of the river) never allowed these pollutants to settle. But that does not mean the river is not polluted. Just because the water seems clean, and it is still flowing does not mean that the river bed, and shoreline are free of contaminants.

This is the current status of a transmission that has never had its fluid change din over 60K miles.

Now imagine if you will, that you add an agent that "loosens" all the pollutants at the bottom of the river and on the shoreline ALL AT THE SAME TIME. This would cause the contaminates to go into the main water stream. Now there is a greater tendency for these pollutants to inhibit a critical area of flow somewhere in the middle of the river.

People who believe in this theory also suggest that if the transmission fluid has NEVER been changed for an extended period such as 60K+ miles, then the best thing to do is to NOT change the fluid, since this will actually give you another 40-60K miles prior to transmission failure which would be a better situation than had you changed the fluid.

In both situations, you're heading towards a new transmission. The choice is whether you believe that a tranny flush will loosen enough crap to actually damage the transmission sooner than had you left it alone.
 

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Sounds more complicated but I think will end up being much easier and quicker than 4x Drain and Fill.
Not so -- fraught with peril. Proceed at your own risk, lest you damage your own transmission.
 

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When a transmission has NEVER had its fluid changed it will build up a significant amount of sludge, but the transmission seems to operate fine since the sludge accumulates over time, and hides it crevasses or walls that are not affected by the main flow of fluid ....until you actually change the fluid.
Respectfully, I am curious: what are the facts upon which you base the several above conclusions. Personal observations? Reports in the literature? Or are you just stating a theory?
 

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This thread has some good info, posted by manualman:

"The Worst Thing You Can Do...."

ATF's serve many functions; here are a few:

1.) Power transmission through fluid power circuits
2.) Friction modification
3.) Heat exchange
4.) Lubrication

Once ATF starts to degrade, it can leave deposits (varnishes, etc.). Once it gets to that point, you probably are already experiencing problems with general operation. In short, if there is enough in the way of deposits on valve bodies, in fluid passages, etc...the A/T is probably already malfunctioning. I don't think adding fresh ATF to a normally functioning A/T via a fluid change will cause the rapid dislodgement of deposits. I've helped open one or two auto trannies back in the day (Ford C4, if IIRC). These had never had an ATF change, had lots of miles on the original filter (okay, it's more like a strainer) ...and I never saw the deposits one would expect, anywhere.

Read manny's post. It's in line with how I look at this topic. Also, I still think that if there's enough junk in there that you're worried about the fresh additive pack in new ATF (friction modifiers, lubrication enhancers, detergents) will cause deposits to dislodge and wreck things...well, the A/T is probably already malfunctioning.

OF
 

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Respectfully, I am curious: what are the facts upon which you base the several above conclusions. Personal observations? Reports in the literature? Or are you just stating a theory?
I just want to chime in on this.

I've only done the 3X ATF drain & fill but I have looked at the other method that drains from the ATF return line.
The 3X drain and fill method is almost idiot-proof but takes time and 9-10 quarts. This is also the Honda-recommended way.

The drain from ATF return line takes less time, doesn't waste as much ATF but requires better multi-tasking skills which I may or may not have.

For the drain from return line method, the worst case scenario is the ATF level is allowed to drop too low with the engine running. Will it cause any damage to the pump and the trans ? I don't know and don't want to find out.

Let's consider 2 cases:
1) If I pour fresh ATF using the ATF fill opening which is quite large, then I am sure I can pour as fast or faster than what comes out of the smaller ATF return line. So the ATF level is less likely to drop too low. No problem here.

2) If I pour fresh ATF using the dipstick tube, then it's possible I cannot pour in as fast as the old ATF draining out. Reason is I am pouring the ATF through a very small dipstick tube opening using only gravity while the old ATF is being forced out by a pump.
So there's a real possibility that I could let the ATF level drop too low.

I've flushed the power steering fluid by opening the return line and pouring fresh fluid into the reservoir.
I could not keep up with the the P/S pump and the fluid level in the reservoir drops very low allowing air into the line, causing a high pitch whine from the pump.
Good thing is the P/S pump can run dry momentarily w/o damage and it's easy to bleed air from the P/S line.
 

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Respectfully, I am curious: what are the facts upon which you base the several above conclusions. Personal observations? Reports in the literature? Or are you just stating a theory?
I'd read about this before, and heard about it from a few mechanics, and did not believe it. So when I bought a used Accord that had never had its fluid changed in the last 80K miles, I decided that all of this stuff was just hype to get people to "ruin" their transmission sooner by not changing the fluid, so I decided to ignore the warnings, and I flushed the fluid, 3 times. The tranny died within 2 months.

I figured that was just a fluke, so the next Accord I bought hadn't had the fluid changed in about 60K miles, and I flushed the fluid on this one as well. Within a month or so, the tranny developed some serious slipping and erratic shifting. The tranny is not dead, but the fluid change definitely stirred up something in there.
 

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This thread has some good info, posted by manualman:

"The Worst Thing You Can Do...."

Read manny's post. It's in line with how I look at this topic. Also, I still think that if there's enough junk in there that you're worried about the fresh additive pack in new ATF (friction modifiers, lubrication enhancers, detergents) will cause deposits to dislodge and wreck things...well, the A/T is probably already malfunctioning.

OF
Manualman sums it up really well: "If you suddenly introduce new high detergent ATF into that environment, great globs and chunks might come off and clog screens and small orifices."
 

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george, that last sentence was his opinion, and he used the word "might"....he doesn't know any more than you or I do about these deposits that can be dislodged, but raised the possibility that this might happen. The top part of manny's post was borrowed from Click and Clack (the "Tappet Brothers" of the CarTalk show), and is spot-on.

As before, I've pulled apart just a couple older A/T's, and haven't seen these "deposits". Chances are your A/T's were on their way out due to neglect before you did the long-ago-needed fluid service.

My 1998 Accord had no service record of an ATF change in 174,000 miles. I drained it, and it was black, pitch black, like thin, waste motor oil. I changed it...7 times...over the course of a couple weeks. It is running more smoothly, and is approaching 178,000 miles, and is running on a full load of ATF-Z1. If there was ever a candidate for an A/T dying due to dislodged deposits, this car is either going to be the poster child for the theory, or it will debunk it.

I don't subscribe to the theory of a fluid change causing demise of an A/T. The evidence is anecdotal, like all the guys who changed fluid on their Gen 2 Odys, only to have the A/T grenade shortly thereafter. In those cases, it wasn't the ATF, it was that 3rd clutch.

OF
 

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Holy crap guys. Is the world ending along with the OP's 60k tranny or what!

Do the 3 or 4x ATF dropp and refill proceedure and have no worries.

Dont listen to all the hub-bub about sludge and needing a new tranny. Cause even if that were true, does that mean you shouldnt do anything at this point? Just run'er till she dies? Get real.

People are over reacting and creating panic...ignore them.
 

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...Dont listen to all the hub-bub about sludge and needing a new tranny. Cause even if that were true, does that mean you shouldnt do anything at this point? Just run'er till she dies? Get real...
Exactly. With 170,000+ on the odo, and pitch black ATF, there's no way I'd even consider not changing the fluid. It's gonna get fluid changes UTK until the drain fluid is red (that's why it took 7 changes).

OF
 

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I'd read about this before, and heard about it from a few mechanics, and did not believe it. So when I bought a used Accord that had never had its fluid changed in the last 80K miles, I decided that all of this stuff was just hype to get people to "ruin" their transmission sooner by not changing the fluid, so I decided to ignore the warnings, and I flushed the fluid, 3 times. The tranny died within 2 months.

I figured that was just a fluke, so the next Accord I bought hadn't had the fluid changed in about 60K miles, and I flushed the fluid on this one as well. Within a month or so, the tranny developed some serious slipping and erratic shifting. The tranny is not dead, but the fluid change definitely stirred up something in there.
Based on your own statements, you "flushed" the ATF both times. You should have "drained and refilled" the fluid. The issue wasn't introducing new fluid but the fact that you "flushed" which you should avoid at all costs on a Honda transmission. Just my 2 cents.
 

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You bet it is! Thats exactly what I do. I don't mess around with 3X partial drains or whatever. I brought my '06 into the dealer at 50K and did the full flush. I will flush every 50K for the life of the van. 50K flushes have served me perfectly on all my other rides, too. Do it.
 
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