Confused about drain and fill vs flush

my new truck has 200k and I see nothing in the 18 maintenance records about an xmission service. So I assume I should change fluids soon. I keep seeing u guys warn against a flush and recommending a drain and fill. Can someone please explain the thought process behind this? Thanks.

 

What color is the fluid? I flushed the trans fluid on my corolla at 600k and at 800k it still shifts fine. If the fluid looks super dark and smells burnt a flush would likely kill the trans eventually. If the fluid is still pretty red chances are you’ll be fine.

Drain and fill works fine and is honestly what I typically do. Drain and fill every other oil change keeps the fluid fresh and happy.

 

Many people have a transmission failure after a transmission flush and think the flush ruined their transmission. In reality a flush won't cause a problem. The people with failures already had a problem inside their transmissions.

I myself though don't believe in doing a transmission flush. I just do drain and fills every 30k miles.

 

I've been doing drain and fill every 20k or so for 230k miles. I wouldn't mess with a flush because it costs labor and I'm a cheap bastard with trust issues.

Do a drain and fill and see what the old fluid looks like. Then in a thousand miles do another drain and fill. You should have pretty good fluid by then, now you can start a schedule.

 

You have a 2000 it looks like.

Mine is a 2002 with the similar A340f transmission.

Follow me on this. Its easier than an oil change on our trucks.

Go to Walmart and buy Valvoline Dex/Merc for about $14 a gallon.

Drain your transmission just like an oil change. About 4 quarts (1 gallon) should come out. Fill the new Dex/Merc down thru the Transmission dipstick using a $3 funnel.

Drive a few months and do it again.

Flushing is complicated to do right (pros only) and can cause problems if done wrong.

Drain and fill just like an oil change but easier and cheaper and no oil filter needed!

Or, if your fluid is real dark and nasty have a shop do it all (proper flush) at one time and then you can do the drain and fill technique explained above for basic interval maintenance.

 

In addition to the great advice already stated above, watch this video.

 

I remember watching this last year and it motivated me to do regular short interval drain and fills.

My 2002 had 4 ‘flushes’ at service shops performed at 50k, 115k, 130k, 145k miles. Not sure which technique they used. The first 50k one was done by Toyota and I ‘think’ they underfilled it because it began slipping b/t 2nd and 3rd gears right after. Took it back in right away and they ‘fixed’ it.

I have no idea what they did. All I know is she seems to shift better now at 166k than when it was newer.

The older a vehicle becomes the more shorter the change cycles are needed compared to when they are newer.

 

Great video.

 

Or you can do like I did and waste two months of your life trying to track down the last of the world's supply of Dex III and do a complete drain by removing the pan. Then replace the gasket, re-install the pan, and fill the trans with the new fluid you found after far too many hours and days searching. That's about 13 to 14 quarts of fluid, setting you back well over $120. [In hindsight, time poorly spent, regardless the outcome.]

Or do as the others suggest regarding the type of fluid and a commitment to regular service. I'm inclined to think that if your old fluid isn't blackened and burnt, the 4-quart drain and fill on a regular schedule, similar to the motor oil drain and fill, is probably the better method to care for your transmission.*

Now if the fluid is indeed burnt, I would proceed as I stated earlier in this post BUT probably go with the Type 4 fluid that Toyota recommends, again to the tune of 13 to 14 quarts. Expensive, but the fluid will be of one type, which is very important according to tranny experts, and meeting Toyota's recommendation.

*Keep in mind the rule of thumb which states that you don't want to mix fluid types. So if one is unaware of the type currently in their transmission, it behoves them to do the full drain and fill to the tune of 14 quarts. Then, as long as you use the same type of fluid, you can go to the 4 quart drain and fill regimen for future servicing.

Lastly, the problem with flushing, as I see it, is the chance that you might stir-up sediments, to include possible metal shavings, that might lodge in the gears and causing the tranny to fail. My thoughts are mine only, but I would rather do several complete drain and fills before doing a flush.

 

This comes up a lot, and there seems to be confusion surrounding the word "flush". Let's see if we can add some clarity.

For starters, some definitions:

1) Drain & fill: as simple as it gets. Remove the plug, drain the contents of the transmission pan, re-install plug, and refill with the same amount of fluid that was drained. This replaces about 1/3 of the total capacity of fluid in the transmission.

2) Flush: remove the output/return line from the transmission cooler, run a piece of vinyl tubing from the cooler output to a one gallon container with quart markings, start the engine and run it until 2 quarts of fluid is pumped out (about 10 -15 seconds), turn off engine. Add 2 quarts of ATF through the dipstick tube, and repeat until the fluid coming out of the cooler looks as clean as the new fluid going in. This is generally done following a drain & fill.

3) Power Flush: this is a service sold at some repair facilities and dealerships. It requires special equipment that connects to the tansmission cooler lines, then draws old fluid out of the transmission and pumps new fluid in.

The Power Flush (#3) is the service that's frequently warned against that can apparently have some ill affects -- although I have no first hand experience with the process or any resulting problems.

The Flush (#2) is perfectly safe and will give you the best results for replacing the fluid in your transmission. It operates the transmission exactly as it operates whenever the engine is running. The only difference is that instead of recirculating old fluid, you're removing it, and replacing it with new. It will take a lot of fluid -- 20+ quarts -- to do properly. But you'll know you're starting with a transmission full of clean, new fluid. Follow up with your periodic drain & fill (#1) and your transmission will last a long, long time.

This process has been done for decades with RWD Volvo cars which use a similar Aisin Warner transmission (in fact the later model 960s and V90s used this exact A340 transmission). Automatic transmission failures are virtually unheard of in those vehicles even with many hundreds of thousands of miles.

 

Good explanation on flush. One which never sinks in on most people.

 

I gotta say I was real jealous of those pure DEXIII quarts you got with all that fancy French writing on the bottles.

 

thanks for all the reply's. I gained some knowledge from the video and the explanation in the diff between a flush and power flush. I checked my fluid while hot this morning, i would say it is somewhere between good condition and needs replacing. so drain and fill here we go.

 

Before any of this, I would get the truck warm and check the transmission fluid level. This will give you a starting point on how much to add or not add when you do this. If it measure within the lines, you can measure what comes out and put the same amount back in. Obviously if its low, you can still measure what came out and figure out how much to add after that.

 

Most Toyota dealership parts counter dudes should tell you exactly your "Drain and Fill" quantity. I have always used Toyota Genuine ATF as specified for each of my vehicles for cheep insurance and piece of mind. Do every other motor oil change until you see nice red colored ATF on your clean white wipe off rag/towel.

 

I drain cold and fill cold. Assuming the proper amount is in before the initial drain, then the temperature is a mute point. Definitely get the engine up to operating temp when checking the levels. I like mine as full as possible up to the top most notch when hot.

 

I disagree. Do you check your trans level hot or cold to get the most accurate reading? Again, this is assuming the proper level is in before you start but if you check it hot, you will already know. I do my engine oil the same, nice and hot.

I am offering this tip because I assumed mine was at the correct level, measured what came out and put exactly back in what came out. As I pointed out in the thread, mine was a quart low to begin with unknowing to me.

 

Playing devils advocate...
I will never understand the point of measuring what comes out in order to put the same amount back in. Especially if all you are doing is a drain and fill.
Do you do that for your engine oil too?
The owners manual states how much fluid is needed for a drain and fill.
Drain the pan. Fill it up as the manual states and then follow the manual's instructions in order to verify the correct level. If it's low add some. If it's high drain some. It's not rocket science.

 

First thing is the spec in my 2002 manual is improper. It states 2.1 quarts and it is clearly wrong as the 2002 needs at least 4 quarts refill. What is the correct recorrected spec? Anyone?

Secondly, I do it as a ball park guide. This is very useful, especially when doing it for the first time. Also, lets me see the fluid. Smell and taste it too. Kidding on the taste.

Third, I’d hate to overfill and redrain even a little bit and then up and down from under the truck multiple times to correct.

 

Engine oil hot to warm is preferred during a drain change.

Per the trans: My point is drain cold and its a cold fresh refill out of the bottle. The new product isn’t heated before putting it in, which leads to my last point.

Those with dipsticks on their transmissions: Do you notice the wide range between cold and hot ranges? Each temperature has its own tight range thats proper. Thats because transmission fluid CONTRACTS/EXPANDS at a large rate. Much greater than engine oil which only has a L and F reading on the dipstick.

What ever your method this needs to be accounted for. In keeping with KISS, I drain cold and fill cold.

*edit: But check level when at operating temp per the manual spec.

 

Our method is foolproof. As Hand Sensei mentioned, it's a proven fact the owners manual has a typo on how much fluid comes out. Way off actually. Your analogy with the oil isn't apples to apples. When you drain the oil it ALL comes out, or at least 98%. When you drain the transmission pan you only get out maybe 1/3 of total fluid. Therefore by measuring it, you don't under or over fill it.

 

So I’m going against the grain here and going to discuss what I did to my 4runner. I have no experience with a Tundra yet, but this seems to work fine for the 3rd gen 4runners. I learned this from Timmy the Toolman, a little bit of a legend in the 4R community and very knowledgeable. I would be interested in the opinions of other regarding this practice for Tundras as I pick up mine next week.

For the 4runners, the suggested practices are 1) the drain and fill measure described here, and 2) a faster drain and fill method that I would consider closer to a flush. It involves removing the supply line to the transmission cooler, in the case of the 4R, it supplies to the radiator. This hose is held to a drain pan and the truck is started and ran until about 3qts or so is pumped into the drain pan. Then, a funnel is used to replace the 3qts of fluid. This process is repeated until the supply hose pumps clean fluid. Fluid level checked and I think I went through 12-14qts just to make sure it was definitely clean.

 

As mentioned above, commonly referred to as a flush. (not to be mistaken with a power flush)

BTW, it’s the same tranny in the 3rd Gen 4Runner and the Tundra.

Flushing these transmissions has been common practice for decades.

 

Not exactly true, the 3rd gens have an A340,some 1st gen tundras have the A750, but that flush method is the same

 

I’d do the Timeh Tool method if I was unsure of the vehicle condition prior and trying to bring it up to fighting shape.

Knowing that a vehicle has been well maintained short cuts right to the drain and fill (4qt.) method which is plenty sufficient, easier, and requires less work/learning curve.

 

This all day....the trans fluid you put in needs to be the same temperature as the trans fluid you drain if you are trying to match the two capacities.

 

Yes indeed. The expansion of transmission fluid is huge when heated.

 

Finally got around to doing the drain and fill today just as u guys said I got around a gallon out and replaced it with Valvoline Dex/Merc.
The old fluid was a little darker shade than the new, no burnt smell at all.
I may be imagining it but I swear it shifts better after the change. I didn’t shift poorly before, but I could definitely feel the shifts. Now it’s so smooth it’s hard to tell it shifted. Am I imagining this or is that tone expected?

 

Your new fluid is working its magic right away just like it does on mine. Thats a good thing.

 

I don't think you're imagining it at all. I felt a difference when I changed the fluid in my Tundra at 94K. I'm guessing it was original fluid.