I noticed that my shifts were getting ever so slightly firmer and harsher lately (my wife wouldn't have noticed it), so I went into get the transmission fluid changed. Its the original fluid at 84k miles. The guy said it was pretty dirty, but not horrible and certainly better than some he'* seen before. I had him change the filter while he was at it, and actually only paid $112 after taxes at jiffy lube for the whole job. My car now shifts noticeably smoother and more quickly than before, which alone is an indication that it was due for that transmission flush.

This is more for peoples' future reference than anything; my observation and recommendation for other Bonneville GXP owners is that for optimal transmission life, you should have your transmission fluid and filter replaced no later than 75k miles.

I'm a firm believer in preventative maintenance, and transmission flushes are one example I can't stress enough. All too often people get their transmission fluid changed only when they start having more severe problems, at which time its already too late. A $120 transmission fluid change is a lot cheaper than a $2000 rebuild.

Hmmm that might explain why mine'* been getting rougher here lately. I've got 104K on it and have no idea if the fluid has ever been changed

That'* **really** pushing it for one transmission fluid change. What color is the fluid?

No idea I've only ever checked the level (Yes you may hit me now for my ignorance lol)

Lol! At least you found this thread before your transmission went kaboom. Check the fluid, and if its brown, head over to your nearest shop ASAP and get a fluid flush and filter change done.

Just checked and its kinda an orangish-red color

That actually sounds normal. Aged, but normal.

I'm not too familiar with the 4t80-e trans but dont you need to go pretty deep to get the filter?

Probably did get changed then before I got it.

And it has two "chambers to empty", did he get both?