Transmission fluid flush vs drain and replace fluid

Maintenance/Repairs
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1

I have been negligent regarding the timeliness of replacing my transmission fluid on my 2007 Honda CRV. Have 70K miles without changing and was told by dealership that it should be drained and refilled because it was no longer pink-ish in color and was brown. I asked about flushing and they said something about the pressure may damage the “celenoids?” and cause the transmission to not shift smoothly. I asked 2 different mechanics at local gas stations and they each said to flush it (although one said that if the fluid was black he wouldn’t advise flushing and just replace, and the other said that if over 100K, that flushing could cause the transmission not to shift smoothly).

The dealership wanted 120 to drain and replace, the gas station mechanics want approx 240 to flush.

I would like to perform one or the other and am seeking advice as to which.

Thanks.

2

I think that your manual suggests a fluid change at 100k miles, so while it would have been nice to change it earlier, you have not been negligent.

If your fluid is badly discolored at 70k miles, I fear that you have a problem, so it may not much matter whether you drain or flush. Do one or the other and cross your fingers.

Remember that draining the fluid gets only about half of the fluid out, so you will be mixing fresh fluid about 50/50 with old brown fluid. For that reason, I would tend to want to flush it. However, this is not the first time I have heard that Honda does not recommend flushing their transmissions, so I guess it is best to believe them. It should be pretty easy to drain and replace your fluid. There is even a video doing it on a CRV on uTube. However, if your fluid is discolored, you may want to clean the screen and the pan, and that will be a lot messier. Honda also insists that you use their fluid, but a Google search should identify the manufacturer of their transmission fluid so you can probably get it cheaper elsewhere.

Some folks say that putting fresh fluid in an old transmission causes it to fail. That is like observing someone die after taking aspirin to ease the pain from a brain tumor and concluding that the aspirin killed them.

3

I’m guessing your manual says just to drain and replace it, possibly three times. If so, that’s what I’d do.

As Manolito says, you may be heading for trouble in any event, so keep your fingers crossed.

4

There must be 50 threads about this exact question. Right under the Ask a Question button is a search box.

5

My 2005 Accord owner’s manual says to drain, not flush, the fluid. The pressure fro the flush pump may be high enough to damage the solenoids. Get the engine (transmission, actually) well warmed up and then drain the fluid on a flat surface. You will get at least 70% of the fluid out. Replace the fluid and you are good to go. If you are concerned about the remaining fluid, perform another drain and fill cycle immediately. IIRC, the Honda recommendation is to drain and refill twice (3 fills total) to remove essentially all the old fluid. You can do this easily yourself and don’t need special tools. You will need a narrow ended funnel to fit into the transmission dip stick tube. That is where the fluid is added. The fluid will cost about $24 for 4 quarts.

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I work at a Honda store and the 30k by the book is a full fluid/filter exchange. Oil, trans fluid, brake fliud, per steering, and coolent all get changed out for fresh.

7

Your dealer is right, although $120 seems high for something that is basically cheaper to do than an oil change. There is no pan to drop or filter to change on a Honda transmission. The gas station that told you it was black should be avoided completely.

Honda does recommend their own fluid, and they have come out with a new synthetic fluid, DW-1. You might find something that is equivalent somewhere else, but it will be just as expensive.

8

I work at a Honda store and the 30k by the book is a full fluid/filter exchange.
Oil, trans fluid, brake fliud, per steering, and coolent all get changed out for fresh.

gsragtop:
When you make reference to “by the book”, are you referring to the maintenance schedule published by Honda motor corporation? Or are you referring to maintenance schedules often published by dealerships?

9

It looks like you have an automatic transmission.

First you need to make sure you follow the manufacturer’s recommendation as a start.

I strongly recommend replacing the fluid at least every 30 or 40,000, even if the manufacturer list something longer.

Do not every wait until there is evidence of a problem. Transmissions like to hide their needs until it is too late. It is like going to the doctor. You want to see your doctor once or twice a year, just to make sure.

Doing so has saved my life. That little spot that did not look right, sent me to the doctor. The next day I was on the operating table with the possibility of waking up with only one leg. Getting to the doctor early saved my leg (over 40 years now) That transmission is the guy who put off seeing his doctor, or did not want to pay for the office call.

10

Drain and replace with a Honda transmission. Retail for DW-1 is $7ish/qt (use this ONLY). The best method for full replacement is drain/refill/drive until lockup in transmission twice. The final time simply refill.

My Acura take 3qts/fill not sure what a CRV does(likely similar).

Never flush a honda transmission.

The service monitor in my Acura came on at 70k for transmission so previous owner changed it. The 30k recommendation is prudent but may not be what Honda actually recommended if you have the service monitor in yours. Eg the Service A or B or C followed by 123456

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This is why I’m bumping up this old thread. I need you guys to help me decide on what to do with my Lexus IS transmission fluid without having to start another tedious topic.

The user manual for my 2018 300 AWD Lexus IS makes no mentioning of a transmission fluid service but everywhere I’ve read on the internet so far is saying I need to have the transmission fluid flushed at 60,000 miles. Then there is the strong opposing opinion saying to never flush but to drain and refill.

Toyota dealer told me themselves I needed to change ( flush ) at 60,000 miles but Lexus dealer counteracted that by saying it should be flushed at 90,000 miles.

The user manual doesn’t say which or when. It’s completely silent on the matter.

The guys on the Lexus forum said the transmission must be serviced, and as I stated earlier, they fight over flush and drain/refill.

Then there are those who said to never service the transmission as it is sealed, and customers who said they never changed theirs during the life of the car never had an issue.

I’m so confused. I believe I brought this matter to CarTalk before, too, but my memory can’t hold everything that’s going on in my life. So see with me.

12

Listen to reason.

Tester

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13

Thank you.

My car will get serviced at 70,000 miles soon and I will request a transmission flush.

14

As if you were not already confused, I will put it another way, on your A760H transmission, you do have a serviceable filter, so it needs to be changed also if the fluid was never serviced at a higher milage (you should be OK)…

Some transmissions don’t have a pan to drop, and or a serviceable filter, so only a drain and fill or flush can be done on them…

Some pans have a drain plug and those transmissions without a dipstick will have a fluid level/overflow plug somewhere on it or a fluid level check/overflow plug/bolt in the pan that under the correct conditions will drain out any excess ATF to a perfect level, yes you deliberately overfill the transmission when adding the fluid by a 1/2 to 1 quart amount, but never drive it until level is correct…Meaning you can just do the recommended drain and fill, however you are not replacing all the ATF as Testers video explained… Now with a pan drop, you can replace about the same amount of fluid as a drain and fill, but you can also replace the filter… With the flush, you are replacing 100% of the fluid, but still no filter… However if the transmission fluid does not look like it has much debris in it, and not burnt or have an offensive odder to it, then the filter should be OK, but if 1st time servicing the trans at 100K, I would replace the filter…

Now with all that being said, it would be better to flush and then pan drop with a new filter on most geared autos with a serviceable internal filter…
But on most Toyota/Lexus models, they seem to do pretty well with only drain and fills regularly over the life of the vehicle… If using the correct Toyota fluid fore it…

Also anytime a flush is done the fluid level still needs to be checked properly, even though you might put in the same amount that came out of it, that doesn’t mean it was full to begin with…
The Tacoma’s have been documented that most-a lot of them left the factory low on fluid, to the point of some even slipping,… Now since it takes time to even properly check the fluid in these, no scan tool will tell you the level, most, not all, new car prep trucks are not even being checked, but checked off on by the mechanic, mainly cause they may only get paid 2 hours to check it out and that includes the test drive, to check the fluid level takes about 30 minutes start to finish, and if not done within about 8 minutes window or so while the fluid is in the correct temp range, the trans will get out of check range and you have to let it cool down and start all over, I think the 18 or 19-23 may have eliminated one step but still time consuming, therefor most are not being checked even when asked to be checked… So a flush may not be filling them to the proper level either… I am sure the Tacoma’s are not the only ones being done like this out of all the manufactures out there including Toyota…

It is my understanding that CVT’s should never be flushed…

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15

Given your situation, it’s safer to go with the dealership’s recommendation to drain and refill the transmission fluid. Flushing can sometimes cause issues, especially if the fluid is old or the transmission has higher mileage. A drain and refill is less risky and will still improve the condition of your transmission without potentially damaging sensitive components like the solenoids.

16

It is also possible to do a few (3) drain and fills over a short period of time and that will get most of the old fluid out…

17

Both Lexus and Toyota recommended a flush over drain and refill.

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Toyota Transmission Fluid

A transmission fluid change is frequently half the price of a transmission flush as it requires various less fluid and time to function. Toyota transmission fluid changes are extremely crucial to keep your vehicle’s transmission bleak and lubricated. If you don’t routinely change your fluids at least every 30,000 miles or so, you may find that your Toyota transmission will slip. Check your car’s owner’s manual for more information on the disparate mileage intervals in which your transmission needs the fluid changed.

Toyota Transmission Flush

A transmission flush is frequently twice the price of a fluid change due to the discard of time the service takes and the fact that the flush not only replaces the fluid in the pan but also removes fluid from the cooler lines and added parts of your transmission. A Toyota transmission flush also uses about 10 quarts of fluid to entirely clean and flush out the system.

A transmission flush is only vital if your system contains dirt or debris . If the fluid is highly dark or contains back-up sediments, we would recommend a complete system flush instead of just exchanging the fluid.

Toyota Transmission Filter

Changing your Toyota transmission filter isn’t as easy as further filters in your car. There are multiple components to your transmission filter including the filter itself, which is frequently a metal plate with a fiber material that catches pollutants. Your Toyota will also contain a pickup tube, gasket, and rubber seal which may all need to be replaced along with the filter. Your Toyota transmission filter will need to be replaced every 30,000 or 50,000 miles. Be sure to check your vehicle’s maintenance guide for more information on mileage and time intervals.
The above is courtesy of Toyota of Greenville Dealership…

If doing every 30K to 50K, you should not have any/much of that, anytime the fluid is drained, it should be collected and checked for debris from clutch material as well as the steals and any other metals in the fluid, if more than normal, then the filter needs changing…

With yours being almost 70K, then yes a flush would be better, but remember if the fluid is that dirty then the filter is still dirty and needs changing… Other wise if doing it in the 30-50K miles, then a drain and fill will work, 1st time at 100K, flush and pan drop with new filter…
I have seen Toyota transmissions go 500,000 miles with no servicing, although that is NOT recommended at all…

Remember those same dealers gave you different advise for the same work…

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IMO the Lexus and Toyota dealers recommend a flush so that they don’t have to come back to you if just draining the ATF shows enough debris that it should be flushed. I think a lot of customers would feel cheated if they had a drain and filll followed by a flush.

20

Quite right . . .

I’ve known a lot of guys that measure the amount of old fluid they remove, refill with the exact same amount without actually following the correct fluid check procedure and then pat themselves on the back, reasoning that the fluid level was correct to begin with :roll_eyes:

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