Changing transmission Fluid...A Very Big Gamble?

[rodburg]

Hey guys, i have a 03 I35 with 142k on the odo. The car was in a lease and its obvious that it was not taken care of properly. I have no way of knowing whether the transmission fluid was changed before however i can speculate that it has been. The transmission doesnt slip nor does it kick. The fluid does look bad and has a very slight burned odor. I know that changing the fluid is very risky. It could be beneficial or it can ruin the transmission. My mechanic suggests that i do it . Can anyone share their expirience with the flushing the transmission or any cautionary tales .Many thanks,

Sincerely,

Rod

[MinisterofDOOM]

Flushing a transmission with questionable history can potentially worsen existing problems, but simply changing the fluid is not bad.

Certainly changing bad fluid for good is better than a transmission failure due to old fluid. Even though without a flush you technically won't be able to get ALL the old fluid out, at least you'll be replacing some (probably most) of the worn (less effective) fluid with new. Remember that automatic transmissions are fluid connections, not mechanical. To work at optimum efficiency and effectiveness, it needs good fluid with good viscosity.

I highly recommend that you do some searching for topics such as "transmission fluid" "transmission flush" "drain and fill" "fluid exchange" in the Q45 forum (don't forget to try searching new AND archived posts, and search post bodies as well as titles if you're having trouble finding results). The topics have been covered pretty extensively there so there's a lot of info just waiting to be read.

[Mike G]

Personally, I would drain and refill, about three times over the course of the next three months, then feel at ease... At least you will be pumping cleaner fluid through the system and lessen the potential for clogging valves.--Mike