I'm new to the forum and reading all this talk about these trannsmissions is making me depressed. I have a 2001 LXi auto whose trannsmission crapped out a while back at 95k. Since then I put another unit in with about 55k on it. The tranny feels pretty good but up until it hits opperating temp I think its slipping a little. Heres why. When warm the engine runs 2100 rpms at 60 mph. But up until it gets warm the engine revs fluctuate between 2100 to 2500 rpms at 60 mph. But never more. Do I need to worry? If so Roger if your reading this I think I'm gonna be giving you a call in the near future. I still have the old tranns to play with.

Will Do. But again does anybody know if that slippage is normal or is it actually a problem.

If the car is not completely warm yet and you get on the highway, your transmission just isn't warm enough yet. When your rpms "fluctuate", it's not that something is wrong with it, it's that the tranny is still cold and it hasn't kicked in to overdrive yet. Mine's the same way. It will stay in 4th and the rpms will "fluctuate" a little bit to keep the carm up to speed until the car is warm enough then it will drop into O/D.

Does it happen with a constant load on the engine? If so then that is not normal and may not have to do with the transmission at all. if your transmission slips it'll probably go higher than 2500 rpms

Well to try and sum up all the questions I'll explain exacly what happens. It shifts all the way to forth. I can't tell if it's doing it in any other gears because I just do Highway driving before it gets warm. But 4th gear at 60 mph when cold it'll rev all the way up to 25-2600 rpms gradually. As in not very suddenly. Then at just about the same point every time (5 miles or so) I'll get on the gas to climb  hill at it stays at 2100 rpms. I know it's not rapidly shifting back to third like some of you asked because 3rd at 60 mph is like over 3 grand. When pulling a hill it goes to 2500 but when i let off it will gradually work its way back down to 2100 and the gradually back up to 2500 on the next hill. When I put the tranns in I did not have it flushed but I called the dealer today and they said they did put in ATF-4. But at the time I did not get it flushed. That is next on my priorities.  At the time of original post the tranns had only been in like a week so I was concerned but now I've seen it's doing it very consistantly so I'm not as worried. It may be worth noting though that up until it gets warm I stay light on the throttle anyway so it may actually have the ability to slip more, but I refuse to apply enouph throttle to let it go over 2500 rpms. Really I'm just hoping for it to last long enouph to get the old tranns rebuilt and beefed up to handle a good bit more Horse power. Oh and just a thing, I thought that 4th was Over Drive?

Seriously, it just sounds like the O/D isn't engaging yet b/c the engine is still cold...

It's the torque converter. That is normal