The fluid was low in the trans. I reported this awhile back. Once, while on a slope, I shifted into reverse and the trans hesitate for a second before doing a hard shift into reverse (had a similar instant of the car seemly not in gear and then hard into gear shifting into first after backing out of a parking space; I had just gotten the car at the time and was not sure what had happened) Checked the fluid when I got home and noticed it was low. Meant to buy fluid and add but forgot about it. Trans shifted fine. Yesterday after driving about 18 miles I had an issue where I thought the trans may be dropping out and then going back in gear, I refer to it as the car bumping. I am trying to track down a PO171 and PO507 (I had a small evap leak code that I thought I had fixed). I started home and the car did the "bumping" thing again. Return back and checked the fluid and it was rather low; down below the last hole on the dip stick (the hole furthest from the tip). I borrowed a vehicle and got some fluid and filled the trans. Started back home and the car did the "bumping thing" a few times and then stopped. I figured the servos/solenoids/valves may have had air/foam that flushed on out; drove the car back home the 18 miles without any more instant of the possibly trans problem. The fluid looks old and smells old and I checked and it has never been changed as far as the previous owner knows. Filters get clogged and can reduce the pickup; so I am thinking a change in oil and filter is due.

I have done at least two transaxles where I did not do such; no problems. Are GMs trans different in this regard? I understand that valves and the passages can wear but usually the clutches just wear out do the slight slippage before the servos completely engage the clutches and they lock. I would just buy a rebuild trans then and do a swap. In that case, I should just buy another used car LOL considering what rebuilt trans can go for. At this time I have not notice what would be slippage so I am not rebuilding the trans at this time.

I went out today to look at the trouble codes and I have a new code, PO102 added to the PO171 and PO507. Perhaps it was not the trans at all. Could this bumping/bucking have been from the engine? PO102 is related to the MAF and PO171 could be caused by problems with the MAF; so perhaps the MAF is faulty; could this cause the symptom I am experiencing? I did remove the MAF and clean it although inspection showed that it did not appear to be dirty as well as removing the IAC and cleaning off any gunk on the pintle.

I drove the car to go pick up the trans filter kit and it did the stumble/bump thing several times on the way home. I think that might be from the trouble codes; it could be the engine misses or something along that nature.

Those could very well be the causes of stumbles and misfires. Also, if there are driveability issues, it can also affect the way the computer treats the transmission, especially when MAF and TPS issues are involved.

Wow, this starts out as a few questions on fluid and a rebuild, and now we find out, codes are involved, that are creating concerns that may not have anything to do with the tranny......are you related to my last Service Writer?

LOL, no, we had been intended to change the fluid and filter because of the colour and smell of the oil. The original question was important because I would have probably put the DexIII/Merc fluid but this forum educated me and I did searches as well because of the forum. I got the Dex VI last night; not that easy to find here even at the auto shops, one had only one brand Dex VI and plenty of the Dex III/Merc fluid. The thing with not going into reverse on the hill was probably low fluid, dirty filter, and not picking up the fluid or foaming the fluid.

WalMart is my preferred source for dexVI.

We had bucking problem'* on cars most time light throttle going up hills even small ones were its under more of a load {8 times in a row} so bad you think was transmission.
Plug wires was all ways bad some 1 year old even Delco wires every thing is just made in china now and reboxed in what ever brands the box says.

Case in point went to 5 auto supply'* looking at ac compressors brands as such as 4 seasons everco and other name brands all had one thing in common
same casting numbers
and same supply address on the box.
All made in Mexico so when they come in they put SAME PART!!! in different boxes

Go to auto zone look at new duralast water pump write down casting numbers.
Then go to advance or other and look at some name brand guess what same casting numbers.
I could go on and on
There is a few left as MOOG but most are long gone as far as American made quality.

what i did while back was take out 1-2 quarts and add some new atf in through the dipsticks. gain a thousand miles and then repeat. then eventual to the transmission filter.

the whole point was to slowly adjust it to new fluid. i was worried about potential shock with taking out that amount when pan dropping.

however, i chose a brand that isn't dex6. i used one that accepts up to dex3-h. happy shiftin'