Hi All,

I've got a 1995 Bonneville with about 135k on it. I bought it used around 80k. As far as I know, it has the original transmission fluid in it.

I'm thinking about trying to follow this procedure to change the transmission fluid. I don't just mean a drop the pan and drain routine, if you read this procedure you can see it has you pumping out 90% or more of the old fluid.
https://www.amsoil.com/faqs/ATF_and_...Procedures.pdf

I'm curious if anyone here has done this sort of change before, and if so, if you have any thoughts or recommendations on how to proceed? Similarly, I'm curious if anyone thinks this is a bad idea. I'd rather not kill my car

-Josh

Amsoil is a reputable company and I think that procedure would work. I would have tried it that way if I new about it. Just changed my fluid about 2 months ago. Dropping than pan is a very messy job. I had a nice big piece of cardboard under the car and glad I did. I let it drain over night but still was not able to flush out the torque converter so I have a couple of old quarts left in it. You will be amazed out how much goo will be on the bottom of the oil pan.
Mike

Soem times putting nice clean fluid in a old trans can cauae problems. I suggest dropping the pan and changing the 7 quarts that way. Then do it again in 6 months if needed. There'* a write up on doing that in the tech info section. Follow that and it'* not to messy.

if it doesnt look burnt i wouldnt do it period

Why not? GM recommendation is to change it every 100,000 miles, isn't it?

And I've heard the opposite--that if it looks/smells burnt, then don't change it, because you're just going to kill your transmission. E.g., here'* a guy of that opinion :

When not to flush:

Before draining or flushing you should pull the dip stick and look at the fluid. If it is dark, burnt smelling, and you see little flakes or speck in it, DO NOT FLUSH IT. The fluid and transmission is TOAST, but the transmission just has not figured out it should die yet. In these cases for reasons no one has figured out yet, if you flush a transmission in this condition it will fail right away. Real strange, but that is what seems to happen. If your trans is in this condition just drive it while you save for a replacement transmission. There is no way of telling when it will fail. It might be today, next week, or next year, but it is doomed.

The goal here is to flush the trans BEFORE the fluid gets rancid. What you are taking out should look like what you are putting in. Do not wait for a color or smell change. My 4Runner Owner'* Manual calls for transmission fluid change at 30,000 mile intervals. The industry standard it two years OR 24,000 miles which ever comes first. It is your truck, you decide what is best for you.

Link (scroll down to the end of the page):
Transmission Flushing

That'* talking about flushing, dropping the pan and changing the filter and fluid is different.

Well, yes, but my point is, if it'* bad to do a complete fluid exchange when it smells burnt, why would you want to wait to do a partial fluid exchange (drop the pan and drain the fluids) until it smells burnt?

And actually he'* talking about either. Note the first thing he says is "before draining or flushing..."

It'* the only way to change the filter, if the fluid is dark it'* a good bet the filter is getting plugged. If that happens the trans stops working. Older trans always have a chance they will fail after a fluid change. A flush increases the chance of a failure.

So you wouldn't ever change it so long as the fluid is still good and red?

The fluid on my Bonneville is fairly dark, but it doesn't have any unusual smell to it. Of course, maybe I just don't have a good nose for transmission fluid burnt-ness.