Another transmission flush or drain and fill thread

[octanejunkie]

*In a Canarsie accent*
"So Tony and I was talking about transmissions and it seems there are two ways to go, "drain and fill" or "rush to flush". And how about those filters, change em or nah? We don't want no trouble, but what says you guys?"

In all seriousness, after reading a bunch of threads of drain and fill vs flush, I'm comfortable to go either way and see benefits (pros/cons) to both. What say y'all?

• Drain and Fill over a few cycles
• Flush and Fill all at once

Regarding filters, also a hot topic like in this thread, is the concensus NOT to change the filter and just throw a Magnafine inline, or what?

ps. no flame wars pls :grouphug: thanks

 

[mountain mike]

I had the Toyota dealer do a flush on mine. I'm not sure if my tranny fluid had ever been changed, and I wasn't comfortable doing just the drain and refill a few times. However, not long after my pan started leaking. I had that replaced and then added the tranny cooler and magnafine filter. Smooth sailing since.

 

[theesotericone]

Flush till clean trans fluid is coming out then call it good. Drain and fills are fine but there's still old fluid mixing with new. I'd be curious to see how much fluid each method takes before you have truly clean fluid. I know the answer for the flush method so maybe some drain and fill guys will chime in?

 

[LittleCaesar]

Kind of like do I want or need a 4wd or can I live with a 2wd?

I'd say a flush, DIY style, is in order.

 

[jgue467]

Either is fine. But if you have some sort of issue like delayed cold shifts (not the standard 2-3 when tranny is cold but 1-2 and 3-4 or other shifting issues a "rush flush" is best.

Otherwise drain/fill is ok but of course we all know changing 1/3 of the motor oil and refilling with new only yields "dirty" motor oil still going round and round and most of us wouldn't do that huh?

I don't bother with the toyo OEM filter, it's too course to make much of a diff, go magnefine if concerned about small particles.
:cowboy:

 

[19963.4lsr5]

I buy a few gallons of Supertech DexIII at Walmart and drive a week and drain and fill. Replace the oil with the amount you drained out. Hint it's usually around a gallon. If your trans filter has never been replaced its worth replacing or cleaning with brake cleaner and putting the inline filter in.

On the Magnifine filter.....make sure it's screwed together tight so it doesn't leak around the two halves.


Sent from my iPhone using Tapatalk

 

[octanejunkie]

Kind of like do I want or need a 4wd or can I live with a 2wd?

I'd say a flush, DIY style, is in order.

The times in my life I've NEEDED a 4WD I didn't have one, the times I WANT 4WD is when folks on forums poke fun at my steering knuckles being bereft of CV Axles - it's about a 2:1 ratio :cheers:

Either is fine. But if you have some sort of issue like delayed cold shifts (not the standard 2-3 when tranny is cold but 1-2 and 3-4 or other shifting issues a "rush flush" is best.

Otherwise drain/fill is ok but of course we all know changing 1/3 of the motor oil and refilling with new only yields "dirty" motor oil still going round and round and most of us wouldn't do that huh?

I don't bother with the toyo OEM filter, it's too course to make much of a diff, go magnefine if concerned about small particles.
:cowboy:

I've no issues at the present time, just time to replace the trans fluid. I've read a few threads, and had a C4 trans, that used a mosquito-screen filter that was a joke, so if that's all this thing has then I will leave it in place and do a flush

I buy a few gallons of Supertech DexIII at Walmart and drive a week and drain and fill. Replace the oil with the amount you drained out. Hint it's usually around a gallon. If your trans filter has never been replaced its worth replacing or cleaning with brake cleaner and putting the inline filter in.

I'm not sure cracking the pan is worth cleaning THAT filter considering it's never easy to reseal a trans that drips non-stop and it's not a filter that will hard clog. $18 a gallon for High Mileage Valvoline MaxLife Multi-Vehicle seems a good way to go if looking at Walmart, the ones around me don't have Supertech DexIII by the gallon.

I'm kinda interested in a flush fill like this https://www.youtube.com/watch?v=WngXE_7vg-Q and I already have a fluid pump like that.

On the Magnifine filter.....make sure it's screwed together tight so it doesn't leak around the two halves.

Might just do a flush and a Magnafilter like this, no canister, no threads to leak from. 5/16" line might be tight, but 3/8 will be loose - yeah?

 

[mtbtim]

I reckon I'll throw my two cents into this thread. I've been a fan of the easy drain and refill method of keeping the trans fluid in good shape but I probably do it more often than the average person. On previous vehicles, I would do a drain and refill every 30,000 miles. With my 3rd Gen, I've changed that interval to every 10,000 miles.

With every drain and refill, you're replacing around 1/3 of the capacity of the system. So, I figure over 30,000 miles, I've replaced the system capacity. Now, I understand I'm using a dilution process mixing old fluid with new fluid, but I think it does a great job of keeping the fluid in good shape.

With the full flush method, you're waiting a much longer interval to replace the entire system capacity. Say for example you did some mountain driving or towing and you spiked your trans temperature pretty early on after your last flush. The high temperatures you reached lowered the effective life expectancy of your fluid. Now you're going to drive with that fluid for quite a while without renewing it and maybe the lubricating properties of that fluid are going to deteriorate way before you renew the fluid again. So, I feel introducing new fluid at a more frequent interval, even though it's not a full flush, might be better.

 

[octanejunkie]

I reckon I'll throw my two cents into this thread. I've been a fan of the easy drain and refill method of keeping the trans fluid in good shape but I probably do it more often than the average person. On previous vehicles, I would do a drain and refill every 30,000 miles. With my 3rd Gen, I've changed that interval to every 10,000 miles.

With every drain and refill, you're replacing around 1/3 of the capacity of the system. So, I figure over 30,000 miles, I've replaced the system capacity. Now, I understand I'm using a dilution process mixing old fluid with new fluid, but I think it does a great job of keeping the fluid in good shape.

With the full flush method, you're waiting a much longer interval to replace the entire system capacity. Say for example you did some mountain driving or towing and you spiked your trans temperature pretty early on after your last flush. The high temperatures you reached lowered the effective life expectancy of your fluid. Now you're going to drive with that fluid for quite a while without renewing it and maybe the lubricating properties of that fluid are going to deteriorate way before you renew the fluid again. So, I feel introducing new fluid at a more frequent interval, even though it's not a full flush, might be better.

Great points!

Would a full flush AND 10K drain and fills be a good strategy to establish, or reset, a baseline for regular trans fluid maintenance, in your opinion [MENTION=120071]mtbtim[/MENTION] ?

 

[mtbtim]

Great points!

Would a full flush AND 10K drain and fills be a good strategy to establish, or reset, a baseline for regular trans fluid maintenance, in your opinion [MENTION=120071]mtbtim[/MENTION] ?

Yes, I think a full flush followed by 10,000 mile drain and refills would be a solid plan. Some people will probably think drain and refills every 10k is excessive but it's super easy to do and ATF isn't really expensive.

What most people don't know is the life of your ATF is dependent on the temperatures it reaches. If you never get above 170 degrees, your trans fluid could last you 100k. But, under fairly normal driving conditions that includes some mountain driving or steep sustained grades, you can easily reach temps around 220-230. At 220-230, your trans fluid life will only be around 30k. This is probably why the industry standard for renewing conventional ATF is every 30k.

 

[ZionXIX]

With every drain and refill, you're replacing around 1/3 of the capacity of the system. So, I figure over 30,000 miles, I've replaced the system capacity. Now, I understand I'm using a dilution process mixing old fluid with new fluid, but I think it does a great job of keeping the fluid in good shape.

I have always been a fan of the drain and fill method for its ease and short time. However the saying that 3 drain and fills changes the fluid bothers me a bit, but I'm weird and like numbers so I did a little math.

So if you started with 100% old fluid and drain 1/3 of the fluid you are left with 2/3 or 66.67% old fluid and 1/3 new fluid. After 10,000 miles I would assume that fluid has homogeneously mixed. The next drain and fill that you do will reflect the previous numbers. Every subsequent drain/fill will reduce the "old" fluid by 1/3 of its previous concentration.

100% <-- Old Fluid
66.67% <-- 1st Drain/Fill, % of old fluid remaining
44.44% <-- 2nd
29.63% <-- 3rd...
19.75% <-- By this time its all "old" fluid again
13.17%
8.78%
5.85%
3.90%
2.60%
1.73%

In my opinion the drain/fill is better for avoiding fluid change shock, but if changing fluid causes problems there are most likely bigger issues with the transmission. (All theoretical in my mind of course). Personally I would like to try the DIY flush change out.

 

[mtbtim]

I have always been a fan of the drain and fill method for its ease and short time. However the saying that 3 drain and fills changes the fluid bothers me a bit, but I'm weird and like numbers so I did a little math.

So if you started with 100% old fluid and drain 1/3 of the fluid you are left with 2/3 or 66.67% old fluid and 1/3 new fluid. After 10,000 miles I would assume that fluid has homogeneously mixed. The next drain and fill that you do will reflect the previous numbers. Every subsequent drain/fill will reduce the "old" fluid by 1/3 of its previous concentration.

100% <-- Old Fluid
66.67% <-- 1st Drain/Fill, % of old fluid remaining
44.44% <-- 2nd
29.63% <-- 3rd...
19.75% <-- By this time its all "old" fluid again
13.17%
8.78%
5.85%
3.90%
2.60%
1.73%

In my opinion the drain/fill is better for avoiding fluid change shock, but if changing fluid causes problems there are most likely bigger issues with the transmission. (All theoretical in my mind of course). Personally I would like to try the DIY flush change out.

Well, I question your science. You're basically say the old fluid will at some point negate the lubricating properties of the new fluid added. Unless you have some type of chemical analysis to back this up, this is at best guesswork on your part. Temperature is what kills the life expectancy of your fluid. I'm not a chemist, but I'm having a hard time understanding the new fluids lubricating properties would be ruined mixing it with the old fluid.

But, your comment as inspired me to order up a chemical analysis of my ATF. When I do my next drain and refill, I'll bottle a sample and send it in. I have been doing drain and refills since I bought my rig at 111k. I now have close to 170k so this test will either prove my method works or I'm full of shit. Stay tuned.

 

[Scramble]

The times in my life I've NEEDED a 4WD I didn't have one, the times I WANT 4WD is when folks on forums poke fun at my steering knuckles being bereft of CV Axles - it's about a 2:1 ratio :cheers:

"In my Brooklyn,NY accent"

You want freakin' advise & you only got rwd!? Get the fvcK outta here...

:rofl:
:first:

 

[octanejunkie]

I have always been a fan of the drain and fill method for its ease and short time. However the saying that 3 drain and fills changes the fluid bothers me a bit, but I'm weird and like numbers so I did a little math.

So if you started with 100% old fluid and drain 1/3 of the fluid you are left with 2/3 or 66.67% old fluid and 1/3 new fluid. After 10,000 miles I would assume that fluid has homogeneously mixed. The next drain and fill that you do will reflect the previous numbers. Every subsequent drain/fill will reduce the "old" fluid by 1/3 of its previous concentration.

SNIP

In my opinion the drain/fill is better for avoiding fluid change shock, but if changing fluid causes problems there are most likely bigger issues with the transmission. (All theoretical in my mind of course). Personally I would like to try the DIY flush change out.

I'm a fan of the math too, and in reality, drain and fill will never replace ALL the fluid because the fluid ages along the way, but it's a good hedge and will keep the fluid fresh and hedge against aging/breakdown of the fluid.

Now the concept of shocking the transmission with at full fluid change bothers me - it's a machine. Unless the process of the fluid exchange causes an unintended mechanical change, how would one shock the transmission by giving it clean, fresh fluid? I understand the concept and concern, but one could say the same about crankcase oil or any other lubricant in a complex geared machine. I'm not sold on the shock concern... but I'll listen :gossip:

 

[mtbtim]

I'm a fan of the math too, and in reality, drain and fill will never replace ALL the fluid because the fluid ages along the way, but it's a good hedge and will keep the fluid fresh and hedge against aging/breakdown of the fluid.

Now the concept of shocking the transmission with at full fluid change bothers me - it's a machine. Unless the process of the fluid exchange causes an unintended mechanical change, how would one shock the transmission by giving it clean, fresh fluid? I understand the concept and concern, but one could say the same about crankcase oil or any other lubricant in a complex geared machine. I'm not sold on the shock concern... but I'll listen :gossip:

A full flush will only cause an issue for someone who has a transmission that has been abused by not changing the fluid. Once the lubricating properties break down, increased wear occurs in the moving parts, one of these being the clutch plates. That old fluid has suspended clutch material in it and that thickened fluid is helping the the transmission not slip. When you drain all that old fluid out and replace it with new fluid, the suspended clutch material is gone and you end up with a slipping transmission. Also, ATF has detergents in it and I've heard this can loosen up sludge deposits that can get stuck in the fluid channels and valve body and could cause some fluid delivery problems.

I'm by no means an expert in automatic transmissions but I've read up on it pretty extensively and I'm sharing what I've learned.

 

[Mr.X.]

The trans holds 12L of fluid, every time you drain and re-fill you can only displace 4L of fluid max, this fluid then mixes with the old fluid and over time fluid is refreshed. I am guessed it is designed like this for a reason so you don't "shoch" the system. Anyways when I got the car I wanted to do a full flush so I poured a bottle of seafoam in there and flushed the system 2 days later using this instruction:

https://www.youtube.com/watch?v=RumPXivBlk8&t=871s

this worked great for me, and imo best way to do a full flush. I also poured a bottle of Lucas in there for good measure

 

[Buckaroo]

My rule of thumb has been to not change the fluid at all on a high mileage trans that has original fluid or uncertain change interval. The logic is that the friction components wear and it's deposited in the fluid, you change the fluid and the trans starts slipping....I have been advised in the past to drain, save and refill old trans fluid if you have to break into these transmissions.

I am also reluctant to flush older transmissions even if they have had the fluid changed before due to the potential of dislodging sludge in the process that can gum up the valve body....I have been assured, however, by very informed folks (with Ford experience) that this is perfectly fine.There are some transmissions that are more sensitive than others (i.e. Honda). For those, I definitely would not flush.

All that said, I think our T4R transmissions stand up much better than the Honda transmissions so they are more forgiving. But, I do not flush. I fill & drain. And, in all cases, I always use OEM Trans fluid because in many cases (particularly newer vehicles and Honda's). the OEM additives provide some "magic"....

Buckaroo

 

[octanejunkie]

[MENTION=71326]Buckaroo[/MENTION] and [MENTION=120071]mtbtim[/MENTION]
short of quoting your posts, point about suspended friction components taken. I think I will do a drain and fill, saving the recovered fluid, and see what happens. If the trans doesn't shit the bed, I'll drop the pan in 1K miles and check that out.

Now, when should I add that magnetic inline filter into the mix, now or after I kill a perfectly fine working transmission? :flame:

[MENTION=7105]Scramble[/MENTION]
FvcK yov man, yov and the whole roman alphabet :croc::wave:

 

[TonyB66]

Mike, thanks for starting this discussion.

Mike and I had some PMs that got us onto this topic...

Given my current situation where I have little time to invest into the Runner, coupled with what was shared here, I'm going to do a drain and fill, and do so periodically.

Once my house project is done in the spring (hopefully), I'll at least do a flush, as per Tim's excellent video, and maybe even decide to drop the pan, clean or replace the screen "filter", and use a rubber gasket to put it back together.

I can appreciate the "not wanting to rock the boat" approach though.

On the super high mileage T4Rs, those with 300, 400k+ miles, do we know what those owners have been doing with respect to their transmission fluid?

Maybe it's like those folks who live to be 100+ who drink, smoke, eat meat... :dancin:

 

[ZionXIX]

A full flush will only cause an issue for someone who has a transmission that has been abused by not changing the fluid. Once the lubricating properties break down, increased wear occurs in the moving parts, one of these being the clutch plates. That old fluid has suspended clutch material in it and that thickened fluid is helping the the transmission not slip. When you drain all that old fluid out and replace it with new fluid, the suspended clutch material is gone and you end up with a slipping transmission. Also, ATF has detergents in it and I've heard this can loosen up sludge deposits that can get stuck in the fluid channels and valve body and could cause some fluid delivery problems.

I'm by no means an expert in automatic transmissions but I've read up on it pretty extensively and I'm sharing what I've learned.

I totally agree with what you guys are saying. Chemical analysis is well beyond the scope of my original post. Im just saying if you could choose a specific point in time to start fluid changes and you could distinguish between fluid before the first drain/fill and the fluid after the drain/fill it could be argued that there is still about 30% of that original fluid by the 3rd fluid change. For the sake of argument if you had the ability to add up all the different molecules that make up ATF and separate them like two different colors. I like to imagine 100 red marbles in a jar, mix perfectly, take away 1/3 of them, (yes there will be fractions of a marble), but this is all hypothetical anyway. Since all the fluid would be mixed homogeneously then you cant choose to take only old fluid because this is a dilution method as you said before. We all know ATF fluid can last a ridiculously long time if handled with care. I wish engine oil was that way.

When I was referring to fluid shock I was speaking more in terms of the abused transmissions that have black burnt fluid. If you drain that and replace it with new fluid then the transmission will not work because there is no clutch material left. However if you only drain a 1/3 and there is still (2/3) of the previous clutch material suspended in the fluid, it may be reasonable to say that the clutches may still grab but just less effectively leading to more slipping as compared to before the drain/fill.

The summary here is if all we can do is dilute the fluid then there will always be some traces of that original fluid.

I suppose if you wanted to do things for science you could do several drain/fills with shorter intervals and see if the analysis machines can tell the difference.

**Disclaimer** Everything I post here is coming from a flu stricken brain with nothing better to do and should not be regarded as scientifically factual.

Good discussion though. I hope this doesnt turn into one of those "bobistheoilguy" threads. Those things never end.