ok, so i notice my max sometimes shifing hard into second, (auto) so i just ordered some redline D4 ATF from www.myoilshop.com. total came out to $41 ($7 qt.+shipping). anyone have any pointers for changing the tranny fluid? thanks,

Bryan

 

you need more than 4 qts to change it properly. do a search on the subject. you'll find tons of info.

 

i bought 5 quarts

 

do i need more than that? i thought it was about 4 1/2 quarts that would be needed?

 

that's for the first flush. the tranny actually holds closer to 10 qts, but on any drain/fill it'll only pour out about 4.

you'll need to do the drain/fill at least twice.. do the d/f, then drive it for a week and do it again.

 

crap, so i need to order another 5 quarts? thanks for the help so far guys, really appreciate it.

 

in order to do a proper flush, yes..

the best way to do it is to take it to a shop and have them mechanically flush the system. that will take about 12 qts of fluid and cost $100 for the service, but it's the best way to flush the system.

the cheaper alternative is to just change it a couple of times over a short period in hopes that you get most of the old crap out.

 

An even better and cheaper than the machine is to disconnect the side of the ATF cooler line going to the transmission and point it into a bucket. Then, start the car and let about 2 quarts go out. Refill 2 quarts and repeat 5 or 6 times for a nice full flush.

 

I have a question about this: how well is the fluid mixed in the transmission casing? Does the fluid move in a big loop, where it is rarely mixed with other fluid, or do the torque converter and fluid fill areas mix quickly? If they mix quickly, then wouldn't you need more than 12qts to get an effective 'new fluid' purity of >90% ? I calculate that with perfect mixing (which obviously isn't true either), that it would take 20qts of new fluid to achieve a purity of 90% using the method you described above.

 

I would love to see that equation.


The point here is to not pay $80 for a machine that will do the same thing you are doing manually. $80 buys quite a bit of ATF.


I would say the need for performing additional "cycles" depends upon the current state of your ATF.

In my opinion, the only way to "know" how well you flushed the tranny is to take an ATF sample before and after this process:

Your welcome to look at my oil spreadsheet on the 99 Acura TL, where I performed this very method on the ATF, taking a sample at the first flush and after ELEVEN more flushes, which shows an almost nonexistent metal level in the fluid. However, that fluid had not been changed for 66k and more than 5 of these 2 quart flushes were expected.