Drain & Fill Chart

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At one time there was a chart that gave how many drain and fills were required to change close to all of the tranny fluid. I had it all written down and lost it, anyone out there able to find it in the archives, heck I don't even know how to get there.

Thanks in advance
 
This should work.

It's a little more useful than a chart, since the % will depend on your capacity and how much you get out during a drain. It's pretty slick. You have to have Excel for this to work, though.
 
I checked--doesn't look like it's there any longer.

I'll try to dump that other one into googledocs. The other option, if you want to avoid "the man" is to download openoffice and open the spreadsheet in that format. It's free, and if you don't have Excel on your computer, it's good to have.
 
As handy as this spreadsheet is, the cheapest, most green and easiest (in many cases) is to do a DIY flush. After a few flushes, you are dumping mostly good ATF to get into the 80% range and above.

If you are using expensive synthetic ATF, then a flush is the only cost effective way to go.
 
I agree with you. But, there are some cars where a flush is either inconvenient or a really bad idea. I own one of those cars (a CVT transmission with mostly hard pipe, a thermal bypass switch in front of the oil cooler, and a ton of warnings in the factory service manual telling you NOT to flush the system).

For most cars though, I'd agree that a flush is the way to go unless you're on a regular, single drain and fill schedule.
 
jcwit,

If you run out of options, tell us your numbers and we can run the calculations for you and send you some charts.
 
The arithmetic is pretty simple.
If you leave K proportion of your fluid each time (for example, 70% emptying, K = 0.3)
then the proportion of old fluid left after N emptyings and refills is
K**N
or K to N power.

at 70% emptying, using 4 changes, proportion of old fluid is 0.81%

Charlie
 
So after 4 changes with 70% emptying each time the resulting fluid is almost brand new with 0.81 % old fluid?
If so, it is great.
 
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