When to change fluid in newly rebuilt tranny?

[shpankey]

My wifes 2001 GMC Jimmy V-6, 2 Door. 178k mi total. About 1,500mi on the new transmission.

The transmission has just recently been completely rebuilt, as the old one went out on her. Not sure if it's even the original transmission, as I think the transmission specialist may have put an identical transmission into it that was already rebuilt and kept hers as a core.

Anyhow, I decided to change out her differential fluid the other day and I put Amsoil 80w-90 in that. All went well. That was the first time we changed it. Though I think the previous owner had mentioned they had done it right before we bought it. But I honestly don't remember the miles that were on it when she got it. But she's had it for probably 5 years now.

Anyhow, this new transmission, the fluid still look crystal clear on the dipstick. But I have 16 quarts of Amsoil ATF sitting in my garage that was going to go in another car, but it just had a catastrophic failure yesterday. After some reading here, I see it is recommended to change out the fluid after a rebuild fairly soon. Soo.. when should I change it out? Should I do a return line flush or just drop the pan and fill?

 

[Hoosier_Daddy]

interesting to see what is said on this. i have a rebuilt transmission that is going in come spring. the shop i got it from said no breakin process needed and to just change the fluid at the normal interval

 

[Billy_D]

Within the first 5000 miles. Just do a fluid exchange.

 

[exranger06]

I did the first trans service on my Ranger at 22k miles. The pan was spotless, the filter was clean, and the fluid looked brand new. There was no break-in material anywhere whatsoever.

 

[Oldwolf]

I just put a Ford factory rebuilt transmission in my 02 Explorer. They didn't tell me anything about changing the fluid after break in. Usually Ford doesn't say to change it until you get to 100k miles on a new car, but I usually do it at 75k or so.

 

[AdRock]

Personally, I would drop the pan and refill with fresh fluid after 5k miles.

 

[pavelow]

On a rebuilt trans, I'd drop the pan and drain the fluid at 500-1000 miles. It's easy to do and you'll know right away if anything is amiss with the rebuild as soon as you drop the pan.

 

[mechtech2]

If you don't have a filter in line , get one.
They are often supplied with rebuilds.
I'd let the oil change go for a good long time.
Like 10,000 or more. It should not need a flush more than a new factory trans.

 

[bmwtechguy]

I imagine your rebuilt trans came with some type of warranty, usually 12,000 miles or so. I would strongly recommend that you wait until 500 miles before the warranty expires and THEN drop the pan, split open the filter and check the contents inside the filter pocket, if is has that type of filter. IF the filter is clean, then you know all is probably well, and for a long time to come, hopefully. Go ahead and install new filter/gasket and reinstall pan. Then fill/flush out via cooler to get all new synthetic fluid in there. An inline filter such as a Magnefine or SPX Filtran is not a bad idea, either, especially when using a long-drain synthetic ATF.

If you find clutch material or worse inside the filter, then there may be problems. Carry the filter/contents to the builder and show them what you found while still under warranty. Then you may get some help. This is what my builder does. He checks the unit out after 12000 miles/1 year, and if ok, extends the warranty another year or 12,000 miles.

If you break open a rebuilt unit way before the warranty expires, he has more opportunity to blame anything amiss on you or whoever serviced it for you. It is sort of his transmission/fluid until the warranty is up. Plus, no sense in throwing away new/good fluid that early. My builder actually ultra-filters that 12000 mile fluid down to 2 microns and then dumps it back in for another year of use at least.