I bought my present car, an '00 Bonneville SSEi last year at about 100k miles; I switched out the ATF with some store brand Dexron VI, as I've heard good things about it versus older Dexron III (which really isn't a GM forumla any longer). Did filter too at the same time.

Since I drive the car hard fairly regularly, I thought it best to change the fluid and filter every 50k or so. Found Citgo Synthetic Dexron VI for about $5.00 per quart, so used that this time. Old fluid came out with a normal smell and appearance, no signs of overheating, but there was still a fair amount of wear metal at the bottom of the pan, and the magnet was pretty well covered.

I plan on driving this vehicle until the wheels fall off-- I suspect the 3800 Series II engine will long outlast the transmission (4T65E-HD), so with regular maintenance I hope to keep it in good shape.

With that said, how long would you run this ATF between changes? The manufacturer recommends 50k intervals for severe service only.

So did you put on 50k in a year?

There have been some posts on here in the past about people having problems with using Dex VI in a Dex III application. The problems, IIRC, showed themselves within a few weeks or so. So they switched back to Dex III and all was fine.

Dex VI is a better fluid, but it might not work well with all older Dex III spec'd transmissions.

If you use the fluid in your picture, and don't have any problems for a few months, then you would be fine to change it every 50k. Make sure you do a full exchange, or if you do drain and fills our pan drops make sure to do 3 each a week apart, so you get almost all new fluid.

I'd run the 50k interval. It is great fluid, shear stable, etc., though pretty low viscosity. If it was a much older at, I'd say to be careful with elastomer seals, but for you, no worries.

Work fine in my 4L60E in my 98 Chevy truck, FWIW.

Would it be wise to add a bottle of Lubegard Red with his changes? Amazing stuff in many applications.

Bought car in January, had a 50 mile each way commute all last year, separate trips to Maine and Connecticut, three or four trips to Colorado to drop/pick my son up at his mom's. Very busy year. Over $6,000 in gas tallied up in 2011 on www.gasbuddy.com

Id use LG Red in Dex III apps, especially since there is no Dex III license any more.

For VI, I dont think so.

If it's the same engine/tranny combo as my uncle's '95 SSEi, you should be good as long as you keep up w/ the scheduled maint.
He bought that car new in '95, and when he cash-for clunkered it, it was just shy of 300,000mi.

Engine Rebuilt around 175k.

Tranny #1 went out within first year or two( had it in body shop to replace rocker panel taken out by chunk of ice, on way home from picking it up, tranny seized, no fluid!!! methinks someone@ the body shop was tinkering with something they should not have been...)

Tranny #2 rebuilt around..200k... (which would have been aprox 175k from when it went in..)

He spent a lot of time on the road in that car (sales rep for various hardware/plumbing/etc. companies)

I have the 3800 Series II in my camaro it seats a little oil but it still runs like a sewing machine at 182K. When I researched ATF for my Titan I found that Dex VI doesnt play well with Dex III. ive never tried it because the Dex III was just cheaper and there seemed to be no advantage going to Dex VI in my 4L60E

Why wait a week in between? Most transmissions circulate fluid rapidly so just driving it around the block should be more than enough.

"With that said, how long would you run this ATF between changes? The manufacturer recommends 50k intervals for severe service only."

I would go with the mfr's 50K recommendation, considering that the spec'd ATF at the time was DexIII. Since you're now using DexIV, a better fluid, I'd think that same interval should be more than safe.

"Why wait a week in between? Most transmissions circulate fluid rapidly so just driving it around the block should be more than enough."

I did 3 drain/fills from spring to summer last year at 75K miles. Did the first 2 on the same day, driving a few miles in between. Waited about 3 months (about 5,000 miles), and then did the 3rd drain/fill.

When draining the 3rd time, I observed the color of the fluid as it drained, to see how much cleaning had been done in that time (only way to tell with no filter to be replaced). I guess there was nothing to clean because the fluid drained out bright red and clean looking on the 3rd drain. Keep in mind, I had already drained/filled 3 times between 20K and 55K miles. This apparently had kept my tranny nice and clean.