Transmission Partial Drain CALCULATOR **Sticky

[SumpChump]

Here's a link to my Partial Drain Calculator Spreadsheet.

You must dowload it for it to calculate for you, it is an EXCEL Worksheet. Dropbox will just show a preview.

I have seen to many people miscalculating the percents and numbers on partial drains and refills on their transmissions.

What folks commonly say is "if I drain 2 of 6 quarts over 3 times, heck I can have a full changeout by the tuird time..BEWARE! That's not the case... because of mixing, it wont be until the 7th fluid change that you actuially reach a 95% total new fluid.

I used university mathmatics people to design this spreadsheet which is verified as accurate. It gives you percentages, volumes of how much is now old vs. new, it tells you how many partial changes it will take to achieve your desire percent total of new fluid.

Perhaps a Sticky?

Partial Drain Calculator Spreadsheet Link

 

[dlundblad]

15 exchanges for 100%. Wow! This is quite interesting.

The 4th-6th exchange looks a bit more cost effective depending how OCD you are. I am unable to download at the moment, but would it be safe to assume the number of exchanges needed for 100% would increase as the fluid capacity increases? Like a transmission that holds 11 quarts that only drains 6.

**I could just divide the drained amount by the capacity. 2/6.5=30% while 6/11= 54%. I would guess around 9 drains assuming my math is correct.

 

[Lolvoguy]

wow, what a waste of fluid!

 

[SumpChump]

Here's your results.... dlundblad on an 11qt volume pan taking 6qt out at a time

% New Fluid New Required Volume of Old Volume of New Old Removed New Removed
Original 0% 0 11.00 0.00 6.00 0.00
1st Exchange 55% 6 5.00 6.00 2.73 3.27
2nd Exchange 79% 12 2.27 8.73 1.24 4.76
3rd Exchange 91% 18 1.03 9.97 0.56 5.44
4th Exchange 96% 24 0.47 10.53 0.26 5.74
5th Exchange 98% 30 0.21 10.79 0.12 5.88
6th Exchange 99% 36 0.10 10.90 0.05 5.95
7th Exchange 100% 42 0.04 10.96 0.02 5.98
8th Exchange 100% 48 0.02 10.98 0.01 5.99
9th Exchange 100% 54 0.01 10.99 0.00 6.00

 

[gregk24]

Thanks for sharing

 

[SumpChump]

I'm sure you all will just download the Calculator I have linked to play with your specific numbers, which you should.. but here's a quick summary of my findings for "average" passenger autos via my calculator.

It will take about 5-7 Drain & fills to replace to the 95% fresh fluid level for the average 5-7qt transmission. You'll need a total of 12 quarts to accomplish the job. Beware, you should use the calculator I have though since even a half quart drain difference can make a difference.

 

[Le_bow_ski]

Downloaded. Nice spreadsheet. Thanks!

 

[jhellwig]

Good info.

It is impossible to remove 100 percent of the old fluid without removing every trace of the old fluid though but for all intents you could consider it 100 percent.

 

[SumpChump]

Thanks, I hope it helps. It was pretty neat having some academic minds work over the challenge for me and come up with the Excel sheet which I then made more visually appealing and useful.

 

[buck91]

Originally Posted By: jhellwig
Good info.

It is impossible to remove 100 percent of the old fluid without removing every trace of the old fluid though but for all intents you could consider it 100 percent.


Might you say the limit of the percent replaced approaches 100 as the number of changes approaches infinite?

Cool info: 3rd change on the Aurora yields approx. 100% changed!

 

[SumpChump]

Originally Posted By: buck91


Cool info: 3rd change on the Aurora yields approx. 100% changed!


Indeed, I look at the changes that get me at about 93-95% total new as being the highest practical level.

 

[Trav]

Nice! Line off fluid exchanges look better all the time. Thanks for posting this.

 

[demarpaint]

An eye opener for sure. Thanks for posting!

 

[ac_tc]

Originally Posted By: Trav
Nice! Line off fluid exchanges look better all the time. Thanks for posting this.


You still have some internal residue and mixing of oils.

 

[Hokiefyd]

Originally Posted By: buck91
Might you say the limit of the percent replaced approaches 100 as the number of changes approaches infinite?


Yes. In theory, you will never get ALL of the original fluid out. There will, in theory, be an original molecule or two in that transmission for ever. With each change, you get fewer and fewer out, because fewer and fewer exist. It's a curve that approaches 100% as you increase the number of changes, but you will never be able to truly achieve 100%.

 

[paulo57509]

There was a post back in 2005 by "The Critic" that had a link to an Excel dilution calculator. Unfortunately, The link leads to a dead end as far as I can tell.

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=567305

IIRC, there used to be a calculator on Amsoil's web site as well.

 

[jhellwig]

Originally Posted By: buck91
Originally Posted By: jhellwig
Good info.

It is impossible to remove 100 percent of the old fluid without removing every trace of the old fluid though but for all intents you could consider it 100 percent.


Might you say the limit of the percent replaced approaches 100 as the number of changes approaches infinite?

Cool info: 3rd change on the Aurora yields approx. 100% changed!


Yeah you are going to get close but never 100 percent unless you tear the transmission completely down and boil it. But for all intents and purposes you could call it close enough to 100 at 90 or 95 percent.

I would guess that doing pan drops and refills at the sever recommended interval or slightly shorter would be just as beneficial and less wasteful than going at getting 100 percent all at once at the recommended interval. It would still be better than most transmissions ever see.

It still is good info for its intended purpose.

 

[kneesahn]

I can't use or download the calculator as I'm using an iPad as my only source of internet. Would someone please give me the calculation for 10qt capacity transmission with 4 quart exchanges?

Thanks

 

[Scott_mi]

Originally Posted By: fordranger03
Would someone please give me the calculation for 10qt capacity transmission with 4 quart exchanges?

 

[kneesahn]

Originally Posted By: Scott_mi
Originally Posted By: fordranger03
Would someone please give me the calculation for 10qt capacity transmission with 4 quart exchanges?





Dang, I had hoped to be higher than 78% with 3 exchanges. Thanks Scott for taking the time to calculate for me, and thanks Sump for the calculator.