I don't understand multi-drain-and-fill procedures

[tinmanSC]

I'm going to be replacing the trans fluid on my 2000 Lexus GS300, Toyota T-IV. The stealership, amazingly, had it for the not-outrageous-price of 4.35/quart. The car has 90K miles on it and I believe the trans fluid has at least 60K miles on it, but I'm not really sure. I've been reading the different transmission fluid change options and there is something i really don't understand. Why would you do a 3x-5x drain and fill procedure? No matter how many you do, you are still taking out some of the NEW fluid you just put in, and leaving oil fluid still inside the torque converter/cooler/cooler lines. A simple way to do it, as far as I have seen, is to disconnect the transmission fluid cooler lines, start the car, add fluid to the trans dipstick tube as it come out the cooler lines, stop when the fluid looks clear (or you are out of transmission fluid). Turn the car off. Is there a downside here? Aside from the obvious, "don't screw up and run the tranny dry." what is the problem? Faster, cleaner, one shot. Done.

 

[Johnny248]

I've done this many times when I don't have access to the flush machine.

 

[oilboy123]

Better to do the tranny line flush. Some people don't want to mess it up.
The line flush is what I do with the Amsoil tranny fluid. I then never let the fluid get nasty again, problem solved.

 

[Whitewolf]

I can only tell you what I do, and it's expensive and it is going to get a lot of criticism from this site (I can see it coming!!!). The only real way, in my experience, to get anything like a REAL fluid exchange using the fluid that you WANT to use, rather than something that's left behind in somebody's flush machine, is to do a 5x flush. That way, you get about a 99% true fluid change. Expensive though it is, it's a reliable method because with modern fluids (such as DEXRON-VI for instance) you can then run for the thick end of 125,000 miles without having to change again (and that's been proven).

That's my advice, for what it's worth. If you have any questions, send me a PM.

Originally Posted By: tinmanSC
I'm going to be replacing the trans fluid on my 2000 Lexus GS300, Toyota T-IV. The stealership, amazingly, had it for the not-outrageous-price of 4.35/quart. The car has 90K miles on it and I believe the trans fluid has at least 60K miles on it, but I'm not really sure. I've been reading the different transmission fluid change options and there is something i really don't understand. Why would you do a 3x-5x drain and fill procedure? No matter how many you do, you are still taking out some of the NEW fluid you just put in, and leaving oil fluid still inside the torque converter/cooler/cooler lines. A simple way to do it, as far as I have seen, is to disconnect the transmission fluid cooler lines, start the car, add fluid to the trans dipstick tube as it come out the cooler lines, stop when the fluid looks clear (or you are out of transmission fluid). Turn the car off. Is there a downside here? Aside from the obvious, "don't screw up and run the tranny dry." what is the problem? Faster, cleaner, one shot. Done.

 

[JOD]

This exact question has come just come up in another thread, but since you asked it here...

As Onion correctly pointed out in the other thread, if you're filling through the dipstick and draining through a cooler line, you're aren't keeping fluid in part of the system, even if you're filling and draining at the same time; of course, "what part" you're leaving "dry" depends on the design of the transmission.

There's absolutely no way I'd attempt this on my CVT. OTOH, on a Honda AT, what's being left "dry" is basically the bottom of the sump. On a lot of ZF's it's probably the cooler. So, I don't think there's an easy answer, besides "it depends". And I'd beware of anyone pontificating about how "there's no problem, I've been doing it for blah blah". That may be the case on that transmission, but does it apply to yours?

It depends.

Look at the routing of your transmission's fluid and make the determination. If in doubt, do a drain and fill.

That said, remember that if you're getting out 50% of the fluid in a drain and fill (which I think is typical), 3X will give you around 88% new fluid, which honestly isn't too bad.

Another option is a low-pressure DIY machine to refill from the line you've disconnected. There was once an awesome video of a guy doing this on his Volvo. It involved a garden sprayer, some tubing and a pressure guage, and resulted in the largest explosion of ATF I've ever seen! Sadly, I think he pulled the video... He did end up actually getting something to work, though.

 

[tinmanSC]

Originally Posted By: Whitewolf
I can only tell you what I do, and it's expensive and it is going to get a lot of criticism from this site (I can see it coming!!!). The only real way, in my experience, to get anything like a REAL fluid exchange using the fluid that you WANT to use, rather than something that's left behind in somebody's flush machine, is to do a 5x flush. That way, you get about a 99% true fluid change. Expensive though it is, it's a reliable method because with modern fluids (such as DEXRON-VI for instance) you can then run for the thick end of 125,000 miles without having to change again (and that's been proven).

That's my advice, for what it's worth. If you have any questions, send me a PM.

This is exactly what I'm trying to avoid.

 

[JOD]

Originally Posted By: Whitewolf
The only real way, in my experience, to get anything like a REAL fluid exchange using the fluid that you WANT to use, rather than something that's left behind in somebody's flush machine, is to do a 5x flush.


I wouldn't say it's the "only" way.

You can use something like this and this and do your own fluid exchange through the return line as you're draining the fluid. It has a bypass valve and it's low pressure anyway.

Also, If you're getting out 50% each time, I'd say you're really hitting the law of diminishing returns after 4X. I mean, you're up to 93% by then.

 

[eagle23]

Keep in mind that 100% pure, new fluid is not needed. It's an appealing idea, but not needed.

If a trans is having trouble shifting, for example, changing the pan fluid just once results in maybe 50/50 refreshed fluid, sometimes even a bit less depending how much is replaced.

In most cases the trans shifts better, just on that 33-50% percent refreshed fluid. Seen it many, many times.

It seems to be that once you get to 85-90%+ new fluid in the mix, there really aren't any performance benefits to be had. The trannies are very happy like that.

Some might see it differently, and that's fine too.

 

[tinmanSC]

This is what i was thinking. A little bit goes a long way. My GS300 doesn't even have a transmission fluid filter. It's just a metal mesh screen strainer thingie.

 

[wiswind]

I have a 2003 Toyota Sienna with the 1MZFE motor and Asin 451E transmission.
Your 2000 GS300 has the A650E transmission.
My tranny calls for a fluid that meets Dexron III
I did the cooler line fluid exchange using Redline D4.
Redline lists the T-IV as an application for the D4, but you could ask them through their website if unsure.
I have read that folks have been very happy with D4 in the T-IV application.

I DID drop the pan, replace the internal filter, which has a nylon screen for a filter, and replaced the pan gasket.
Here is he first in a series of pictures that show the process.
http://rides.webshots.com/photo/2777272300011220610kWfEeM

I drained the pan, and also drained the "differential" which shares the SAME fluid and is filled when the transmission is filled.
I verified this by putting the drain plug in for the transmission, but leaving the plug for the differential out.....then adding fluid through the dip stick until I saw some new fluid run out the differential drain.
My Sienna is front wheel drive, not all wheel drive, but they still call that unit (Part of the transmission) a differential.

I would recommend that you drain the transmission using the drain plug, and.....if you have a separate drain plug for the differential, drain it also (newer units may not have this).
Verify that you are filling the differential by the same method that I did....just to be safe.

I measured the amount that I drained out and then replaced that with an equal amount of new fluid.
Then I removed the cooler line and directed it through a clear tube into a container, ran the motor at idle until the flow slowed or put out a lot of bubbles in the fluid......refill with the SAME amount of new fluid.....and repeated that process a couple of times.

Dropping the pan gives you a chance to clean the pan magnets and do a visual for any problems, such as large metal particles.
It also gave me a chance to replace the RTV sealant for the pan seal with a real gasket (rubber).

I also added a Magnefine filter to the cooler line that has fluid flowing FROM the cooler to the transmission.
I highly recommend this as it gives you filtration to a nominal particle size of 30 microns and provides a magnet for additional metal particle collection.
The Magnefine filter has a bypass that opens in the unlikely event that the filter media becomes clogged.
They recommend replacing the Magnefine filter once a year.