1995 Bonneville SE 128,500 miles. Transmission shifts fine under steady acceleration but tends to slide, for lack of a better term, into gears while accelerating slowly. I was having this issue a few weeks ago but it was only when the car shifted into over-drive. I started driving the car out of over-drive and just manually shifting it into over-drive once up to highway speeds. I am now experiencing a similar issue driving out of over-drive. Checked the tranny fluid and it is in the operating range. I also notice when the car is in over-drive I really have to mash the gas to get it to down shift.

I don't really know much of anything when it comes to A/T'* but am wondering if it is on its way out.

Having recently lost a transmission to old age, I know the feeling. A lot of things can cause something like this, and low fluid pressure (like from a clogging transmission filter) is the cheapest one to address. Drop the pan, replace the filter, reassemble, refill with Dexron-VI.

If you're having internal transmission wear or damage, you'll probably see it in the form of dark or burnt fluid, tiny metal bits, gunk, or large pieces of whoknowswhat in the bottom of the pan.

If everything looks good, the new fluid and filter should help. My last 4T60 wasn't staying firmly in overdrive before I serviced it. After that, I got a smooth 75,000 more miles out of it.

Thank you for the advice. I am planning on doing this over the weekend. I'm almost to the point where I have more money into the car than it is worth. I just need to get another month out of it and I'll send her down the road.

Picked up a new filter and fluid this morning. I decided to take the day off from work and spend some quality garage time with the Bonneville. This will be my first attempt at doing a transmission fluid and filter change. If there is one positive thing that has come from owning this vehicle. It has forced me to learn and do things mechanically that I would have never otherwise attempted. I've turned this into a personal challenge and am destined to get this car through the winter.

dont wear good clothes, fluid goes every where. maybe thats just me

I have the fluid drained and the filter removed. The new filter came with a seal that looks like a top hat with a hole through it. My Haynes manual shows an o-ring but I don't see an o-ring on the old filter. I felt up in the hole that the filter goes into and can't feel anything like an o-ring in there. Not quite sure what to do now.

After further inspection I located the seal. I however could not get it out of the inlet so I just ended up putting the new filter in with the old seal. I took the car for a test drive and the ol Bonni really liked the new filter and fluid. It shifted quite nice and didn't seem to have any issues with over drive. I'm very pleased!

hopefully it stays, mine did the same at about 155k. i changed the fluid and it felt better for about a week then it completely went. i was able to find a place to rebuild it for about 900

I didn't see a ton of material in the pan. There was some fine paste that was stuck to the magnet. Did you see any larger metal pieces prior to your trans. going out? I'm pretty certain that this is the first time the filter has been changed on this car. I talked to my Father in law yesterday, the original owner of the car, and he said that he pumped the fluid out of it at one time. He couldn't remember if the filter had ever been changed. I'm crossing my fingers that this will last.

it was done once before, i think around 75 or 80. we bought the 98 in 01 or 02 i think. but my wife drives it and she is far from patient. im surprised it lasted to 150k. there was no metal just pasty stuff in the pan. im assuming clutch material.