Idiot moment - Mixed Honda Dual Pump and ATF

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Oct 4, 2008
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PA
Last evenings project was to change the ATF in my Honda CRV and also the rear differential fluid with Honda Dual pump fluid
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You can probably guess where this is going. Changed the rear diff fluid with Honda Dual Pump fluid as I've done in the past, then moved on to the ATF project.

I've changed this CRV transmission fluid yearly by doing a double drain and fill process. Since I do it yearly, I only do the procedure twice, each time draining approximately 3 quarts, running the vehicle, and then draining 3 quarts and repeating. Following this procedure, we are technically refreshing the fluid since only around half of it is drained out and replaced with each fill.

The screw-up occurred when I mistakenly grabbed a quart of dual pump and poured it into the transmission during the first drain and fill procedure. I didn't realize it until I went to do the second drain and fill and realized I had an extra quart of ATF, and an extra empty bottle of Dual Pump fluid.

IF I'm doing the match correctly, since I added a quart of dual pump and then drained the transmission again, I still have 1/2 quart of dual pump in the transmission.

Does anyone know the properties of the Dual Pump Fluid and what effect this could have on the transmission. I've ordered more ATF and will drain and fill at least 1 more time, or possibly 2 or 3 more times to eliminate as much of the incorrect fluid as possible. Any thoughts by the experts who know what fluid this is, if 1 more drain or fill will be adequate or if I should keep doing it repeatedly. Obviously drains and fills are expensive, but damage to the tranny is more expensive.

Any suggestions are appreciated.
 
The dilution ratio is based upon the total quantity in the system, not just how much you drain out. I dont know how much is in the system total.

Seems like a good idea to do one drain to get some of it out and dilute it. In reality, its somewhere between say, 10-20% of the overall system fluid. It may not be enough to make a huge difference in protection or driveability.

How different are the two fluids? If its like two different more or less ATF-like fluids I wouldnt much worry. If its like ATF and gear oil, Id be a bit more worried.

In the end, Im not sure there is much you can truly do but get some mixing, drain, dilute. "dilution is the solution to pollution"
 
In general looking up several model years of CRV on Amsoil's website the transmissions seem to be the typical Honda design, the pan holds about 33-40% of the system capacity, so when you drain you'll be left with approx 2/3qt of the dual pump, then the next DnF you'll be left with just under half a quart, the transmissions seem to hold around 7qts, so that's less than 10%, I wouldn't sweat it, I wouldn't fill a whole transmission with dual pump fluid, but it appears similar enough that having 5-10% of it in there shouldn't be a problem.
 
Anything that goes into a differential could cause havoc with the clutches or friction requirements in a transmission, CVT or otherwise. I would get it professionally flushed and not so much as turn the ignition on before that moment.
 
Thanks for the advice guys.

The fluid analysis information helped a bit with my concern. The wife had to drive the car today about 15 miles for work, and I've been very concerned about it, but having her miss work wasn't an option.

The dilution numbers and capacity given above were pretty accurate. Honda suggests a 4 time DnF with each time replacing a percentage of the total capacity with fresh fluid. They don't publish the total capacity but it is around 7 quarts and they say 2.7 drains out, but I usually get closer to 3.

If I assume 1/3 is drained and refilled, the percentage of old after each Dnf would be below

First change 33/67%
2nd change 55/45%
3rd change 70/30%
4th change 80/20%

Using 40% as the percentage drained, the numbers look a lot better

First change 40/60%
2nd change 64/36%
3rd change 79/21%
4th change 87/13%

So if I put 32 ounces of Dual Pump fluid initially and changed it once before she drove it, there would have been around 20 ounces of Dual Pump Fluid in the tranny.

I'll change it a couple more times and should be able to get the total amount of incorrect fluid down under 8 ounces at which point, the cost of changing it becomes high compared to ounce or two of bad fluid I'm getting out at each change. Furthermore, the fluid analysis shows the material is not completely unlike an ATF and hopefully I've caused no long term damage.
 
Originally Posted by tcp71
Anything that goes into a differential could cause havoc with the clutches or friction requirements in a transmission, CVT or otherwise. I would get it professionally flushed and not so much as turn the ignition on before that moment.


Believe the VOA posted higher up indicates otherwise. I had the same concern - if one is like gear oil with a sulfur based add pack, and the other was more like an ATF, they may not jive. But my interpretation is that this is not the case. Still prudent to flush a time or three.
 
Originally Posted by JHZR2
Originally Posted by tcp71
Anything that goes into a differential could cause havoc with the clutches or friction requirements in a transmission, CVT or otherwise. I would get it professionally flushed and not so much as turn the ignition on before that moment.


Believe the VOA posted higher up indicates otherwise. I had the same concern - if one is like gear oil with a sulfur based add pack, and the other was more like an ATF, they may not jive. But my interpretation is that this is not the case. Still prudent to flush a time or three.

Consider Honda diffs used to be spec'd to use Z1 ATF, then when DW-1 came along they said to use DW-1 in transmissions and Dual Pump II in Diffs. So wouldn't surprise if Dual Pump is more ATF life than gear oil like.
 
Assuming you get 3 qts out of a 7 qt capacity, 4 drain and fills would put you at 90% new fluid. I got this "super duper" excel chart.

Since you have only 14% of the wrong fluid to begin with (1 qt in 7 total qts) I don't know how far to go with drain and fills.

At first change you will have 43% new fluid so you got rid of 43% of the bad qt
At 2nd change you will have 67% new fluid so you got rid of 67% of the bad qt
At 3rd change you will have 81% new fluid so you got rid of 81% of the bad qt
At 4th change you will have 89% new fluid so you got rid of 89% of the bad qt
At 5th change you will have 94% new fluid so you got rid of 94% of the bad qt

May math may not be the best but it should be close.
 
Can you remove a transmission-to-radiator cooler line and flush the fluid?
Say, 2 quarts at a time?
 
Last edited:
Originally Posted by Gebo
Assuming you get 3 qts out of a 7 qt capacity, 4 drain and fills would put you at 90% new fluid. I got this "super duper" excel chart.

Since you have only 14% of the wrong fluid to begin with (1 qt in 7 total qts) I don't know how far to go with drain and fills.

At first change you will have 43% new fluid so you got rid of 43% of the bad qt
At 2nd change you will have 67% new fluid so you got rid of 67% of the bad qt
At 3rd change you will have 81% new fluid so you got rid of 81% of the bad qt
At 4th change you will have 89% new fluid so you got rid of 89% of the bad qt
At 5th change you will have 94% new fluid so you got rid of 94% of the bad qt

May math may not be the best but it should be close.



Thanks for the calculations. Also to clarify, the Drain n Fill is the only method to change fluid. Flushing or feed and bleed through the cooler lines is not recommended.

After everyone's comments, and out of an abundance of caution, I just came back from purchasing 6 more quarts of fluid from a local dealership parts department at their inflated price and will D n F it twice more tonight for a total of 3 changes since my bonehead move
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After the 3rd change, following the math above, I will have around 6 ounces of the bad fluid left which will be diluted with 7 quarts of proper fluid which knowing now that the fluids are somewhat compatible, I'll sleep a little better.

I'll allow the car to be driven again and after the case of fluid I ordered online at a discount comes in next week, I'll do one more D n F.

Thanks again for the advice
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OP, What year is your CR-V and is it front wheel only drive or all 4?

With that information, accurate information about the total system capacity can be found on the Amsoil web site.
 
OP, thanks for sharing your mistake. If I ever do the CVT fluid and rear-end fluid the same day in the future I will know to be sure to keep the fluids separate. Your sharing the information about the possibility of this mix-up may save others from making the same mistake.
 
Originally Posted by JimPghPA
OP, What year is your CR-V and is it front wheel only drive or all 4?

With that information, accurate information about the total system capacity can be found on the Amsoil web site.


He was changing the rear diff and used rear diff fluid in his tranny... Seems like he has a 4 wheel drive CR-V, right?
 
Originally Posted by ammolab
Originally Posted by JimPghPA
OP, What year is your CR-V and is it front wheel only drive or all 4?

With that information, accurate information about the total system capacity can be found on the Amsoil web site.


He was changing the rear diff and used rear diff fluid in his tranny... Seems like he has a 4 wheel drive CR-V, right?

If the front wheel drive CRV is like most other front wheel drive Hondas wouldn't there'd be no diff because it's inside of the front wheel drive transmission?
 
Yes, it is a AWD CR-V that has a rear differential. The rear diff on AWD honda's contains the clutches which adjust the torque to the rear wheels. The front transaxle has a shaft which runs to the rear differential and it was the transaxle fluid (ATF) that I contaminated

Also, as an update, I did drain and fill the transmission 2 more times last evening and will do once more this weekend when I get more ATF.

As an FYI, doing the D n F is a very quick process on a Honda transmission. Its actually faster than an oil change since there is no filter to change. It takes me longer to put the car on the lift than change the ATF.

Pictures of the change below if you've never seen a Honda transaxle drain plug location.

[Linked Image]

[Linked Image]
 
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