kudos to the SumpChump for posting this calculator

Transmission Partial Drain CALCULATOR **Sticky | ATF, Differential, Trans, Brakes, P/S | Bob Is The Oil Guy

so if you drain 6 qts of tranny fluid at each engine oil change, it would take 10 drains to get to 99% replaced tranny fluid. you would be using 60 qts of fluid to refresh 17 qts.


<table style="width: 485pt; border-collapse: collapse;" border="0" cellSpacing="0" cellPadding="0" width="646"> <colgroup><col style="width: 119pt; mso-width-source: userset; mso-width-alt: 5778;" width="158"> <col style="width: 366pt; mso-width-source: userset; mso-width-alt: 17846;" width="488"> <tbody><tr style="height: 23.25pt;" height="31"> <td style="border: 0px black; width: 119pt; height: 23.25pt; background-color: rgb(255, 192, 0);" class="xl74" height="31" width="158"></td> <td style="border: 0px black; width: 366pt; background-color: rgb(255, 192, 0);" class="xl73" width="488">PARTIAL DRAIN HELPER</td> </tr> <tr style="height: 16.5pt;" height="22"> <td style="border: 0px black; height: 16.5pt; background-color: rgb(238, 236, 225);" class="xl65" height="22"></td> <td style="border: 0px black; background-color: rgb(238, 236, 225);" class="xl65"></td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border: 1.5pt solid windowtext; height: 24.75pt; background-color: rgb(238, 236, 225);" class="xl72" height="33">6</td> <td style="border: 0px black; background-color: rgb(238, 236, 225);" class="xl71"><-- Partial Drain & Refill Amount</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: black windowtext windowtext; height: 24.75pt; background-color: rgb(238, 236, 225);" class="xl72" height="33">17</td> <td style="border: 0px black; background-color: rgb(238, 236, 225);" class="xl71"><-- Total Fluid </td> </tr> <tr style="height: 18pt; mso-height-source: userset;" height="24"> <td style="border: 0px black; height: 18pt; background-color: rgb(238, 236, 225);" class="xl65" height="24"></td> <td style="border: 0px black; background-color: rgb(238, 236, 225);" class="xl65"></td> </tr> <tr style="height: 25.5pt; mso-height-source: userset;" height="34"> <td style="border-width: 1.5pt 0px 0px 1.5pt; border-style: solid none none solid; border-color: windowtext black black windowtext; height: 25.5pt; background-color: black;" class="xl66" height="34"></td> <td style="border-width: 1.5pt 1.5pt 0px 0px; border-style: solid solid none none; border-color: windowtext windowtext white white; background-color: black;" class="xl68">[***************]% New Fluid[/color]</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border: 1.5pt solid windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]Original[/color]</td> <td style="border-width: 1.5pt 1.5pt 0px 0px; border-style: solid solid none none; border-color: windowtext windowtext rgb(184, 204, 228) rgb(184, 204, 228); background-color: rgb(22, 54, 92);" class="xl70">0%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]1st Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">35%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]2nd Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">58%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]3rd Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">73%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]4th Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">82%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]5th Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">89%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]6th Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">93%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]7th Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">95%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]8th Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">97%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]9th Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">98%</td> </tr> <tr style="height: 24.75pt;" height="33"> <td style="border-width: 0px 1.5pt 1.5pt; border-style: none solid solid; border-color: white windowtext windowtext; height: 24.75pt; background-color: rgb(22, 54, 92);" class="xl67" height="33">[***************]10th Exchange[/color]</td> <td style="border-width: 0px 1.5pt 0px 0px; border-style: none solid none none; border-color: black windowtext black black; background-color: rgb(22, 54, 92);" class="xl69">99%</td> </tr></tbody></table>

 

So the punch line on this is what? Buy 60qts or pay for a transmission flush?

I hear that the transmission flushes are hard on transmissions b/c the flushing liquid strips out the old tranny fluid and reduces lubrication and is hard on the pumps b/c they push the fluid through with an external pump and don't have the internal pump on. Or something to that effect...

 

It seems like the drain helper is telling you that theoretically a small percentage of the original fluid might remain after a long time. Yeah that's true, but if trans fluid is homogenous than does it actually matter if a teaspoon or three is older than 99% of the rest of the fluid? In practicality eventually you'll average out to the oldest fluid being no more than 4-5 flushes old. The original fluid takes longer to eat through as a layer because it's larger, so if you did a complete trans flush and started the cycle then you'd never have any fluid older than 5 flushes. That's where I've seen people use the interval method, you start with new fluid and that way only 5-10% of the original fluid ever stays in longer than 4-5 flushes, and everything else comes out after 4-5, starting the cycle of none of the fluid ever being "too old".

If you take a 30,000 transmission fluid replacement interval, and need 4-5 changes for complete replacement, then you do a drain and fill every 6000-7500 miles, which would be in line with doing it roughly every oil change "per the book", or twice per oil change if you do the extended thing.

Kind of like this, it's really rough but it was done quick:
(if anyone knows a better way to account for the negative numbers actually being taken out of other layers, by all means have at it. this also assumes an equal amount of each layer comes out and not a proportional amount because hey, i'm not an engineer and this math thing is hard)

<table border="0" cellpadding="0" cellspacing="0" width="1024"><colgroup><col style="width:48pt" span="16" width="64"> </colgroup><tbody><tr style="height:15.0pt" height="20"> <td style="height:15.0pt;width:48pt" height="20" width="64">
</td> <td style="width:48pt" width="64">Batch 1</td> <td style="width:48pt" width="64">Batch 2</td> <td style="width:48pt" width="64">Batch 3</td> <td style="width:48pt" width="64">Batch 4</td> <td style="width:48pt" width="64">Batch 5</td> <td style="width:48pt" width="64">Batch 6</td> <td style="width:48pt" width="64">Batch 7</td> <td style="width:48pt" width="64">Batch 8</td> <td style="width:48pt" width="64">Batch 9</td> <td style="width:48pt" width="64">Batch 10</td> <td style="width:48pt" width="64">Batch 11</td> <td style="width:48pt" width="64">Batch 12</td> <td style="width:48pt" width="64">Batch 13</td> <td style="width:48pt" width="64">
</td> <td style="width:48pt" width="64">s/b=100</td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 1</td> <td class="xl65"> 65.00 </td> <td class="xl65"> 35.00 </td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 100.00 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 2</td> <td class="xl65"> 47.50 </td> <td class="xl65"> 17.50 </td> <td class="xl65"> 35.00 </td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 100.00 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 3</td> <td class="xl65"> 35.83 </td> <td class="xl65"> 5.83 </td> <td class="xl65"> 23.33 </td> <td class="xl65"> 35.00 </td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 100.00 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 4</td> <td class="xl65"> 27.08 </td> <td class="xl65"> (2.92)</td> <td class="xl65"> 14.58 </td> <td class="xl65"> 26.25 </td> <td class="xl65"> 35.00 </td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 100.00 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 5</td> <td class="xl65"> 18.33 </td> <td class="xl65"> x </td> <td class="xl65"> 5.83 </td> <td class="xl65"> 17.50 </td> <td class="xl65"> 26.25 </td> <td class="xl65"> 35.00 </td> <td class="xl65">
</td> <td class="xl65">
</td> <td class="xl65">
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 102.92 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 6</td> <td class="xl65"> 11.33 </td> <td class="xl65"> x </td> <td class="xl65"> (1.17)</td> <td class="xl65"> 10.50 </td> <td class="xl65"> 19.25 </td> <td class="xl65"> 28.00 </td> <td class="xl65"> 35.00 </td> <td class="xl65">
</td> <td class="xl65">
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 102.92 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 7</td> <td class="xl65"> 4.33 </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> 3.50 </td> <td class="xl65"> 12.25 </td> <td class="xl65"> 21.00 </td> <td class="xl65"> 28.00 </td> <td class="xl65"> 35.00 </td> <td class="xl65">
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 104.08 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 8</td> <td class="xl65"> (1.50)</td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> (2.33)</td> <td class="xl65"> 6.42 </td> <td class="xl65"> 15.17 </td> <td class="xl65"> 22.17 </td> <td class="xl65"> 29.17 </td> <td class="xl65"> 35.00 </td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 104.08 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 9</td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> (0.58)</td> <td class="xl65"> 8.17 </td> <td class="xl65"> 15.17 </td> <td class="xl65"> 22.17 </td> <td class="xl65"> 28.00 </td> <td align="right">35</td> <td>
</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 107.92 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 10</td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> 1.17 </td> <td class="xl65"> 8.17 </td> <td class="xl65"> 15.17 </td> <td class="xl65"> 21.00 </td> <td class="xl65"> 28.00 </td> <td align="right">35</td> <td>
</td> <td>
</td> <td>
</td> <td class="xl66"> 108.50 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 11</td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> (5.83)</td> <td class="xl65"> 1.17 </td> <td class="xl65"> 8.17 </td> <td class="xl65"> 14.00 </td> <td class="xl65"> 21.00 </td> <td class="xl65"> 28.00 </td> <td align="right">35</td> <td>
</td> <td>
</td> <td class="xl66"> 101.50 </td> </tr> <tr style="height:15.0pt" height="20"> <td style="height:15.0pt" height="20">Drain 12</td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> x </td> <td class="xl65"> (4.67)</td> <td class="xl65"> (0.58)</td> <td class="xl65"> 7.00 </td> <td class="xl65"> 14.00 </td> <td class="xl65"> 21.00 </td> <td class="xl65"> 28.00 </td> <td align="right">35</td> <td>
</td> <td class="xl66"> 99.75 </td> </tr> </tbody></table>

 

I don't recommend flushes that use a chemical cleaner. I do recommend flushes tha tonly use transmission fluid.

 

It will never be all new. But you can get the percentage of old fluid down pretty low.

Instead of a time consuming spreadsheet, just consider that with each 6 qt change you will be left with 66% old fluid, then 66% of that, then 66% of that, and so on.

(Actually 65%, but it is easier to think in thirds)

Drain No. = %Old fluid
1 = 66%
2 = 44%
3 = 29%
4 = 19%
5 = 12.5%
6 = 8%
7 = 5%
8 = 4%
9 = 3%
10 = 1.5%
11 = 1%
12 = .06%

At 1 change per 5k miles, your 12th change would be at 60k miles, and you would have used 72qts of SP fluid. If you can find SP for $5/qt, the fluid will cost you $360, plus the cost of filters at whatever interval you choose.

Not too bad really, but over that same 60k miles you could have just had the two prescribed dealer flushes at a cost of around $200 each. I'll stick with the flushes. Not worth it to me.

 

Ok, I am NOT a tranny guy. Always had mine done by a good shop and left it at that. But, I can say from personal experience that if you "burn" one, as it torch the clutches, etc, cook the fluid, the only way to get it all out is with a full clean out/flush (and resultant rebuild of course). Same reason you can't reuse torque converter, can't get all the torched fluid out of it.

Well I guess I'm just wrong-headed then? (Wouldn't be the first time)



In my "wrong-headedness", as soon as you start it up, and put it in gear, you just recirculated a large portion of the trans fluid, through tranny and pan. So, your "new" fluid, just got mixed all the way through all of your "old" fluid.

I fail to see any benefit to this at all. I would go with what Bpounds said and just do the prescribed full flush at the regular maintenance interval and be done with it.

Dropping 6 fresh quarts into 11 "old" quarts just dilutes your fresh quarts into meaninglessness.

But I'm probably wrong-headed...?

 

in the 80's NYC GSA used the same approach for motor oil. every 5,000 miles they would change the filter and just add a qt.

The cars got auctioned off to the public after 5 years of use.

 

Since my truck needs the heated transmission fluid flusher machine and my local dealers don't have one, I'm going to drain the fluid and drop the pan to change out the filter. After that, I will put a hundred miles or so on then just drain the pan and refill with fresh fluid.

From what I read on this site and others, this is the best approach if you can't get a heated flush.

 

drain once, drive a 100 miles, then drain again would get you half of your fluid new, half still old. not arguing the methodology just pointing out that based on the charts in this thread, you would need more drain and refills to drain out all the old fluid thru the drain plug.

 

I have wondered about doing the following, and I would welcome Mark Kovalsky's comments.

Drain the pan. Install the plug. Start the engine for a short time. Not sure how long, but the goal would be to get a little more fluid out of the TC, but not do any damage. Call it 30 seconds for discussion. Pull the plug and drain again. Even a couple/three additional quarts out would make a pretty good impact on the chart above.

Questions;
Will this do any damage to the trans or TC?
How much extra fluid can we expect to be expelled from the TC, considering there is nothing in the pan for pickup?
Will the trans reprime itself safely after refilling?

 

would not work on the torqueshift transmission. there is an internal flow regulator that needs to kick in once the fluid reaches 160 operating temp. until the temp is reached, the torque converter will not empty. this is why cold fluid exchange does not work.

 

So make the first drain with the trans up to operating temp. Reinstall the plug and immed. run engine and then drain again........It will still be hot enough to open the regulator.

 

Run the pump dry for 30 seconds? Not in my transmission.

It won't hurt the torque converter, but it will probably destroy the pump.
I don't know for sure, but I would expect something in the range of 2-3 ounces.
Only if the pump isn't destroyed. And I expect it will be.

 

Guess I won't be doing that! ^

Thanks Mark.