Transmission fluid dilution calculator...

[dippschtick]

Can someone steer me in the right direction? Looking for a calculator to figure how many drain and fills to reach as close to 100% new fluid.

My 4Runner supposedly has an 11.3q capacity with 3.2q drain. Found some calculators on line but greek to me.

Should have paid more attention in school.

 

[Pelican]

Originally Posted by dippschtick
Can someone steer me in the right direction? Looking for a calculator to figure how many drain and fills to reach as close to 100% new fluid.

My 4Runner supposedly has an 11.3q capacity with 3.2q drain. Found some calculators on line but greek to me.

Should have paid more attention in school.


Once you know the capacity, just measure what comes out and replace it with an equal amount, just make sure that both fluids are at the same temperature, keep doing this till you've replaced the full measure.

 

[Hall]

Don't aim for 100%, 75+ is more than sufficient. Plus, strictly going by the math, the amount of "new" fluid hits a mathematical point of diminishing return. See below:

Code
Total Fluid Capacity: 11.3

Amount Replaced: 3.20



Change #1 28.32%

Change #2 48.62%

Change #3 63.17%

Change #4 73.60%

Change #5 81.08%

Change #6 86.43%

Change #7 90.28%

Change #8 93.03%

Change #9 95.00%

Change #10 96.42%

 

[supton]

Probably easier to just do a full flush. Pull a cooler line and pump it out. A drain and fill is a small amount of the volume, 28%. Each time you dump, it should get better, but, you're also dumping out good fluid. Presuming that you are doing a D&F and then driving for a bit. If you were doing a drain, fill, run for a few minutes, then repeat... technically it's never 100%. Each time it's what, 0.72 times? First D&F is 72% old fluid left, second is 52%, followed by 37%, fourth is 27%, 19%, 14%, seventh is 10%. 10 D&F's is still 3.7% left.

A 2018 needing a change though? I'm thinking the fluid should be just fine. If you just want to do a D&F every 6 months or a year, ok I think I could be on board with that. But a D&F every week seems like a waste of good oil.

 

[Hall]

Originally Posted by Pelican
Once you know the capacity, just measure what comes out and replace it with an equal amount, just make sure that both fluids are at the same temperature, keep doing this till you've replaced the full measure.

Supposedly these "calculators" factor in how the old and new end up mixed but I've always said there's no way they can be accurate. They just make the person feel better and trust the numbers.

According to the calculator, you have to change the fluid over 10x to reach ~100% new fluid but 3.2 quarts x 4 changes = 12.8 quarts, which is more than the total capacity so (4) changes should be enough, right ? This is why I told the OP aim for around 75% according to the calculator and be happy.

 

[dippschtick]

Originally Posted by hallstevenson
Don't aim for 100%, 75+ is more than sufficient. Plus, strictly going by the math, the amount of "new" fluid hits a mathematical point of diminishing return. See below:

Code
Total Fluid Capacity: 11.3

Amount Replaced: 3.20



Change #1 28.32%

Change #2 48.62%

Change #3 63.17%

Change #4 73.60%

Change #5 81.08%

Change #6 86.43%

Change #7 90.28%

Change #8 93.03%

Change #9 95.00%

Change #10 96.42%


Thanks for doing the math for me! Appreciate cha!

 

[dippschtick]

Originally Posted by supton
Probably easier to just do a full flush. Pull a cooler line and pump it out. A drain and fill is a small amount of the volume, 28%. Each time you dump, it should get better, but, you're also dumping out good fluid. Presuming that you are doing a D&F and then driving for a bit. If you were doing a drain, fill, run for a few minutes, then repeat... technically it's never 100%. Each time it's what, 0.72 times? First D&F is 72% old fluid left, second is 52%, followed by 37%, fourth is 27%, 19%, 14%, seventh is 10%. 10 D&F's is still 3.7% left.

A 2018 needing a change though? I'm thinking the fluid should be just fine. If you just want to do a D&F every 6 months or a year, ok I think I could be on board with that. But a D&F every week seems like a waste of good oil.


Not that I need to change it but have been curious to know the numbers. I've done two drain and fills so far with the Amsoil ATL.

 

[Oro_O]

Originally Posted by hallstevenson

Supposedly these "calculators" factor in how the old and new end up mixed but I've always said there's no way they can be accurate. They just make the person feel better and trust the numbers.


No, they describe what goes on in the physical world, based on well-understood laws of motion and fluid dynamics. As long as the vehicle is driven a bit to allow the static fluid in different areas to mix between drain/fills, they are going to be very, very accurate.

That is why doing a cooler fill at one time is better; you can sequentially do roughly 3 drain/fills, but not mix as much old fluid back into the new. This might get you into the neighborhood of 75 to 80% change using 9-ish quarts, or roughly where you get in 4 to 5 discrete drain/fills.

I have one of these fractional dilution calculators I made in a public google sheets cloud file, you can see it here:

https://docs.google.com/spreadsheets/d/1Q09EgQ9YKJf1Q_qROXvstVO4PMeYGlPTXseqFuq3E54/edit#gid=0

I have added a few columns to give a better picture of what goes on, particularly the "quarts used" and 'quarts replaced' columns, which show you how little reward you are getting for going after those bits of old fluid. It takes 9 drain/fills, with ~29 quarts of clean, new fluid, to get 95% (10.7qts) of clean new fluid into your transmission.

 

[K20FA5]

Originally Posted by dippschtick
Can someone steer me in the right direction? Looking for a calculator to figure how many drain and fills to reach as close to 100% new fluid.

My 4Runner supposedly has an 11.3q capacity with 3.2q drain. Found some calculators on line but greek to me.

Should have paid more attention in school.


Have you done a drain and fill yet on this one? Just curious how it went? Ours is due soon (at least in my mind). Just over 3 years and 35,000 miles. Just curious how difficult/easy it was. Ours still shifts beautifully with the stock WS in it. Just like to do a drain and fill every 40-50,000 miles or so.

 

[dippschtick]

Originally Posted by K20FA5
Originally Posted by dippschtick
Can someone steer me in the right direction? Looking for a calculator to figure how many drain and fills to reach as close to 100% new fluid.

My 4Runner supposedly has an 11.3q capacity with 3.2q drain. Found some calculators on line but greek to me.

Should have paid more attention in school.


Have you done a drain and fill yet on this one? Just curious how it went? Ours is due soon (at least in my mind). Just over 3 years and 35,000 miles. Just curious how difficult/easy it was. Ours still shifts beautifully with the stock WS in it. Just like to do a drain and fill every 40-50,000 miles or so.


I've done two so far. The drain and fill is pretty easy. Lots of tutorials on line (Toyota forums) on how to do it. I have a Scangauge II to check temperature so that makes it a lot easier.

 

[Revving2Redline]

If your going to change the fluid you have to make a mess or spill a bit or you dont get the picture lol.

 

[Oro_O]

Originally Posted by Marco620
If your going to change the fluid you have to make a mess or spill a bit or you dont get the picture lol.


Ha ha, sadly I agree.

I have done so many changes. Even knowing all the pitfalls, getting careful and taping off the ground with plastic sheeting, etc., something always spills. Gotta accept it and embrace the work and goal, not the mess. Good comment you made.