Tranny fluid / filter chage

99 lumina 3.8, 115,000 miles on her.
Maintained well. Mostly highway miles.

Want to do tranny fluid filter change. I too have read both good and bad on doing that with the high mileage. I'm not doing a flush that some places do. Just gonna drop the pan and put new filter and fluid in.
What is everybody thoughts on this?????

Thanks!

When's the last time it was done?
High mileage transmission service usually only offers problems if the service hasn't been done or has been excessively long since it has been done, the reason being that sludge will form around the seals. As the seals wear, the sludge keeps leaks from forming, but when you change the fluid, the detergents in the new batch will deteriorate the sludge build-up and leaks will develop -IF- the seals were going bad to begin with.

I change my 1999's fluid and filter around 10-15k because I do loads of city driving here in Atlanta, but I think the recommended service is like 20-30k now.

to be honest, it has not been done yet. This would be the first one. It is still red in color, and doesnt smell burnt.
What about changing filter and putting old stuff back in? Just a thought...

I've heard from the beginning of time that a partial change is the way to go if the tranny has high miles. I've heard a bunch of different reasons, but Richtazz put forth a theory that made the most sense to me. By replacing all the fluid, you bring the shear strength of the fluid back to new, and it can be too much for older clutch packs, and pull the lining off of them. New fluid will strip away varnishes that may have built up and are cushioning some parts as well. New fluid will generate higher pressures, which may be too much for older seals.

I can't confirm this, but I can tell you that if you want to kill a tranny that isn't acting right, changing all the fluid is the quickest way to do it.

If the service was performed at regular intervals, like 25,000 miles, I wouldn't hesitate to do a full exchange.

Just do a pan drop and filter and replace the 6 or 7 quarts you get out with new. (that's only around half of what's in it)

thats what i was plannign on doing. Service manual says it takes 7.4 qrts of fluid with a filter change. I Think it said the total cap was around 11 qrts or so.

Remember to make sure the old o-ring and sleeve come out wwith the filter, or you have to pull them out. I've found a number of them double ringed and malfunctioning when DIY'ers did the pan drop.

yes i've read that. And read where they didnt change it, and the filter fell out of the sleeve.
The filter kit as a new sleeve, and I was going to replace that as well.
Is the O ring reusable? I didnt notice one of those in the filter box, but i will double check.

thats what i was plannign on doing. Service manual says it takes 7.4 qrts of fluid with a filter change. I Think it said the total cap was around 11 qrts or so.

Sounds right. When I did mine, I started out with 4, added one more and had a reading, drove it around a little to settle it, stick showed nothing, added 1 more, then had to go get a seventh to bring it to midway between the marks, which is how I left it.

Remember to make sure the old o-ring and sleeve come out wwith the filter, or you have to pull them out. I've found a number of them double ringed and malfunctioning when DIY'ers did the pan drop.i,ve got a 98 lumina and also a 95 olds acheiver. ,both a/t with 3.1 v/6,s.both = 65,000 miles. do you know if they both have the same transmissions?? is that a good time to change just fliud and filter? do you think it,s best to bring it to a regular transmission shop for that service instead of my usual shady tree guy?

yes i've read that. And read where they didnt change it, and the filter fell out of the sleeve.
The filter kit as a new sleeve, and I was going to replace that as well.
Is the O ring reusable? I didnt notice one of those in the filter box, but i will double check.

It's all one piece. The rubber is made on the sleeve if it needs it. Some just have the sleeve, no ring. I think mine had a couple of bolts so it couldn't drop, something they didn't used to have. The older ones just had a hook, but the neck could still drop enough to leak and drop pressure.