I've never seen an actual example of a flush causing any problems or accellerating the failure of a trans. I've done flushes on both of my cars. Both with mild issues and high miles.

I vote with drop the pan. I had a problem with 65E at 80K miles roughly. I changed fluid 3 times in 12 thousand miles or so by dropping the pan and changing the filter (had done it at 65K miles). I did not change filter on repeat flushes. Keep the rubber covered gasket from the original unless someone else ha switched already. They help cool the transmission. They are meant to be reuseable.

I replaced about 7 quarts out of 12 by dropping the pan. Next time I replaced 7 quarters out of 12. Third time I replaced 7 quarts out of 12. 41%*41%*41%=7% of original fluid left in trans. Probably same as a flush would have done in one run.

Replacing part of the fluid is not as likely to make a quick change to some clog or crud in the tranny. Buick Service Manager did not recommend a flush. He verified with another service manager who do flushes.

I'm at 135 K and going fine.

Just had a flush on mine with 123,000 miles and it has been acting a lot better since then. Fluid wasn't black but quite dark and smelled a little bit.

if the car has the magnet in the pan won't that stop metal shavings from messing up the gears, so in turn a drain and filter change would not do any harm to the tranny, i just did mine last weekend i don't think it has ever been done and right now everything is smooth. on another note when i droped the pan the magnet was covered in like a half inch of silver grease.

That'* not silver grease. It'* miniature pieces of you tranny suspended in transmission fluid.

i guess it was never done cause it was thick , how often should you drain the tranny