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2013 Corolla - Brown Transmission fluid issue

Hi all,

I’m new here and a dunce when it comes to cars - I did some searching on the forums before making a new post, and I’m not sure if my issue is being addressed. I’m getting conflicting information about how to address a problem with my 2013 Corolla (bought used two years ago at 46,000 miles) - one from my regular mechanic, and another from Toyota.

I took the car in to my mechanic for it’s 60,000 mile maintenance at mile 59,800. It had a few minor issues that I did suspect, but one blindsided me. The transmission fluid is a very dark brown. The mechanic confirmed that the fluid has no odor to it that would lead them to think the fluid is burned. I’m not having any troubles operating the vehicle, nor am I experiencing anything out of the ordinary with it. My mechanic is confident that the transmission is in working condition (At least his technician is). My mechanic recommends a process where they would pump out the old fluid and immediately replace it with new fluid through the same process.

I called Toyota, since the transmission is still covered under warranty and I don’t want to do something to violate it in case there’s a bigger problem. Over the phone they told me I’d need to take it to a dealership, and that Toyota doesn’t recommend what my mechanic wants to do. Toyota wants to do a drain and fill.

My mechanic is concerned if they do that, they won’t remove the old fluid completely and I’ll just end up back where I’m started.

If this were you, who’s direction would you follow - and why?

Thanks again to anyone who takes the time to offer input, I appreciate it!

You don’t have to take it to the dealership for this service.

But you must follow the manufactures service recommendations while the vehicle is under warranty. Otherwise you void the warranty.

Once the vehicle is out of warranty, you and your mechanic can service the vehicle any way you want.

This will give an idea of the condition of the transmission fluid.


You are about to pass the 60000 mile point and you will have to pay for the service. Just make a choice that lets you sleep at night.

Hey don’t wanna hijack thread but I changed my ATF today and was exactly would burned smell like?

Since it’s still under warranty, and Toyota told you to take it to a dealership, I recommend that course of action. Pumping out the old fluid and replacing it with new has a nice sound to it. But if it were mine, I’d have the bottom taken off, a close inspection of its innards, including the filter, a new filter put in, and then button it up and top up the fluid. They do leave some old fluid in there, but what you learn from an actual inspection would give me more comfort. If something serious is wrong, you’d be compelled to rely on the Toyota dealer to fix it under warranty. You might as well start trusting them.

Just a drain and refill and not the exchange. Just like the book says. I do mine at 30,000 though.

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A simple drop & clean the pan, replace the filter (if applicable), and fill with fresh fluid is what I’d do. I wouldn’t allow the use of fluid exchange machine by itself, often called a flush. But if they want to combine the processes, drop & clean the pan etc, then use the fluid exchange machine to do the re-fill, that’d be fine, perhaps even better than a simple fill, provided the fluid in the fluid exchange machine isn’t contaminated.

Good for you for being on your toes on this.


Regardless of what you do for replacing the fluid, you certainly want the dealer to examine it now to get any issues documented while the car is under warranty. If this were my car, I’d just let them do the drain-and-fill after that. If you’re concerned about leaving some old fluid behind, you can do multiple drain-and-fills. (My previous car called for doing it three times at each service, for what that’s worth.)

A simple drain and fill every 2 engine oil changes for my Corolla.Doing it often keeps the transmission fluid clean so I dont’t have to drop the pan and flush the system.

Take it to the dealer. Many manufacturers today, including Toyota, use an ATF that is formulated for their transmissions. An independent mechanic is more than likely going to use a universal ATF that can damage your transmission. This is especially true if they want to use a flush machine.

A drain and fill will only remove either 3.5 qts or 4.1 quarts from a total of around 7 quarts. The pan has a drain plug and if only the drain plug is removed, it"s 3.5 qts. If they drop the pan, it’s 4.1 qts.

There are a couple of techniques to getting most of the rest. The first is to do several drain and fills each a few miles apart. That never gets it all but two the three gets enough. Just on drain and fill gets enough if the old fluid isn’t too far gone.

The other technique is to drain and fill, then hook up to a fluid exchange machine and cycle through another 3.5 to 4 qts of ATF.

The fluid exchange machine (flush) by itself never gets it all. It is drawing fluid out from one part of the pan and filling from another. It is constantly diluting the ATF with fresh, but never gets it all.

My daughter bought a new 2003 Corolla which I believe has the same transmission. At 75k, the ATF was almost black. The service manual claimed the ATF was good forever and never needs changing, but clearly this is not the case. I did two drain and fills, one I dropped the pan and cleaned it out, then 500 miles later, I just dropped the drain plug and refilled.

The transmission was just starting to give my daughter some shifting problems. This cleared them up. I have drained (plug only) every 30k since then and the vehicle has over 200k on it now. The transmission has worked flawlessly ever since.

I don’t know where you people get your info from, but a tranny flush machine replaces ALL the fluid.

That’s why the pro’s use them.


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Sorry @Tester, but your link only makes a claim, it does not offer an explanation as to how it gets all the old fluid out.


Never heard of hydraulics in a loop?

Look it up!


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Its not a loop. You have a reservoir, you are drawing fluid up through the filter from the center of the pan and replacing the fluid from the return cooler line. All you are doing is diluting what is in the reservoir.

Now if the reservoir is drained and filled first, then you are drawing clean fluid in and expelling the old as it comes out the cooler. Or you remove the pan and filter and connect directly to the pickup and drain from the cooling line, that would be a loop.

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Study this.

It’s called a hydraulic loop


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My understanding is that a transmission flush machine keeps putting fresh fluid in until the operator sees clean fluid coming out and this usually takes up to twice the transmission fill volume.

Also, a flush is not recommended for fluid that has never been changed in 100k miles or more because it could dislodge stuff that plugs things up. A local independent shop will not do a flush on neglected trannies because of comeback trans failures he’s experienced with flushing.


The technician fills the machine with fresh fluid that equals 10% over the fluid capacity of the transmission.

The engine is started, and the pump within the transmission is what causes the fluid exchange.

On Honda vehicles, the transmission must be placed into drive for the pump to engage.


Nothing to study here, that is not a transmission. But it is interesting that the cooler has two inputs but no output.