changing tranny fluid on old car

I got this 1991 cavalier and has 155K miles on it, still running strong though. Never changed transmission fluid EVER on this car for over 155 K miles. Would it be a good idea to change the tranny fluid now?????

There is always a possibility that new fluid can cause a problem especially in a tranny with that many miles. The other problem is that the filter is probably so clogged it isn't working correctly. If you are having issues with the transmission then change the fluid and filter otherwise leave it alone.

If the car is in that good a shape, change the filter and fluid. Go with a premium ATF fluid and as a bonus put a bottle of lucas in there. The lucas should loosen anything up that may be sticking. GTP Dad is correct,there always is a possibility that at this stage of your cars life having never changed the fluid or filter after that many miles that you could possibly do more harm than good. I doubt that it is probable. I believe that you have to weight your options. I did it on my 94 RS with 122.000 on it at the time. My car now is at 165.000 That was over 2 years ago. Runs like a dream.

Definitely change the tranny fluid, flush, fill and new filter, it is certainly possible to harm the tranny by doing this, but I had a similar situation and did a flush and fill and had a tremendous improvement (although, I didn't think anything was wrong with it beforehand ) . chances are u will notice the difference immediately.