Cooler Line Exchange Efficiency

[RF Overlord]

Originally Posted By: Jim Allen
The exact replacement oil is TBD... I have the obligatory agonizing period to finish before I pull the trigger on the best right choice.
I think we've ALL done that, Jim.

I just finished a 3 month agonize over whether to use Pennzoil Conventional or Motorcraft 5W-20 in my DD in the spring. Was in Wally's the other night and noticed my hand reaching for a jug of MC so I guess the choice was made for me.

 

[Donald]

The problem with a drain and fill comes after the 2nd or 3rd drain and fill. You are dumping ATF that is more than half new to get another 10% or 15% new ATF in the total percent.

You will be ahead with a cooler line exchange if you drain and fill the pan before you start.

The unknown here which no spreadsheet can figure in is what % of the ATF that the pump pushes into the transmission is returned to the pan and what goes out to the cooler before coming back to the pan.

I'd assume it varies and we really do not know for sure, thus cycle through a few extra QTs of ATF to make somewhat sure.

 

[SHOZ]

I think the usual route for the fluid is out of the TC and through the cooler back to the pan. The little bit that is in the valve body and clutch packs is what does not get changed.

It's a pretty dramatic color change from the old fluid and the new when you pump it out after stopping the first time.

This procedure is from the Ford manual and I would think if they recommend this method it is the most complete way to do things. Unless you can drain the TC somehow there will always be some old and new fluid. But when I did it I always ended up with fluid that looked like new.

 

[KrisZ]

When I did the cooler line exchange on my Mazda I used clear vinyl tubing. I did not drain the pan beforehand, just let the transmission pump out the fluid.
I was able to pump out roughly 3 quarts each time which is pretty much the same as the drain. Total capacity of my AT is 7.6 quarts per the manual and I could see through the clear tubing that the first 1.5 cycles (about 4.5 quarts) were dark and opaque. It was only towards the end of the second cycle when the fluid pumped out started to get clear and by the end of that cycle it was pretty much as clear as the new fluid. I performed a third cycle, pumping out a total of roughly 9 quarts.

I'm fairly certain that I got the vast majority of the old ATF out, whatever small amount was left behind doesn't bother me one bit.

 

[SOHCman]

No one wants to wast ATF, but skimping a couple quarts of flush fluid on a multi-thousand dollar trans is penny wise pound foolish.

 

[Jiblet]

Originally Posted By: Ramblejam
Originally Posted By: Jiblet
I'd like to see more info or other reports of efficiency for the transfusion method.


"...while exchanging more than 90% of the fluid"
http://www.boschdiagnostics.com/dsoftware/2213699_ATX300_SELL_1011.pdf

"will yield in excess of a 90% fluid exchange in a single pass"
http://www.rtitech.com/documents/2009%20...REV%2016-17.pdf


Thanks for the links!