Transmission Service? keep old fluid or put new..

I don’t think any service technician worth anything would ever put fluid back into a vehicle, particularly transmission fluid. Opens them up to too many possible issues down the road should something fail.

I'm with the new fluid bandwagon.
Especially if they needed to replace the trans pump for some reason.

Make sure they flush the cooler lines, and replace the converter if it hasn't been done.

Pumps on these things is not cheap.
Pump damage is usually caused by the converter.
(Assuming this is a 6l80)

BG1988 said:

i see, i heard people changing the fluid and the transmission never worked good again

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Only way i see that as a thing was when you had so much crud and varnish built up, that the new fluid began doing it's clean action and pushed stuff into the solenoids.

(Thinking of an experience i had with the 4l60 with my s10.
That was my first run fixing a transmission (valve body))

Or the fluid was changed on a failing transmission, and it was just blamed on the fluid change.

they did not change the fluid they said only a small amount came out....

i'll do the service later on at 110k

i don't think there is any varnish build up since there is no Thermostat.. RPO: Thermostat Delete .. the temp on the DIC display only shows 145F winter to 165F summer I have never seen above that

Remember everything GM put in at the factory came for the LOWEST bidder.

BG1988 said:

What do you guys think about doing a transmission service

it's 11qt that need to be replaced after swapping out the transmission pump (it has to be drained before service according to the dealer)

should i reuse the old fluid or put new fluid I got 12qt at $5.27/qt from oreallys auto parts
valvoline dexron 6 Full Synthetic (officially licensed )(NOT muti car formula ) (priced match walmart)

also a new drain plug on the transmission pan and aux pump it's 10$ but i don't want a leak

the SUV has 106k on it the fluid is clean no glitter

View attachment 366773View attachment 366774

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Please tell us that this is a joke!

One risk if attempting to use old fluid is some contamination picked up from containers and funnels used. Sounds like you might be due for a complete fluid flush/change. Do it.
Are we really to the point of trying to save $6 vs. the labor to save the fluid? So maybe save $3.

adventurenali92 said:

Wow is that what these millennials are doing these days is reusing old transmission fluid?!

Putting the old fluid back in the transmission kind of defeats the purpose of changing the fluid out doesn’t it?!?!

Like others have said why is this even a question?!

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I'm not a millennial but don't blame them for this nonsense, this is straight old bomber mechanic crap.

the saying goes if you have a ton of miles on a tranny, say 200k. just leave it alone, don't disturb the fluid. it might start to slip. I doubt there's any truth to it but no one has ever said to reuse the fluid, that's just silly, especially when a normal auto only drains a few qt with a filter change. the rest is left in the converter and tranny itself. but this isn't a normally tranny. he has a Allison made hybrid tranny, it doesn't have a converter and will drain most of it out. the pump. he's changing is eternal.

I have a 96 4l60 with 320k on it, I have a vacuum oil collection at work, I use it to suck out the fluid out of the dip stick tube every few oil changes and top back off from fresh because it's free for me. tranny has never given me issues and it had over 220k when I got it like 12 years ago.

The new fluid will always have better conditions than a used one. However, if a transmission already has serious damage, new or old oil will not make a difference.

Put in new. And flush ALL of it. Back in late August 2019 I put in a new deep pan on my 2010 Yukon XL 2500 (6L90 transmission). When I did that - I also changed the filter and flushed all of the fluid. Use quality Dexron fluid of whatever the correct type is. I don't recall reading anywhere that the synthetic stuff is really worth it. The biggest hassle was draining the fluid from the original pan - which had no drain plug. I ended up buying a Mityvac MITMV7300 evacuators. First I used that for getting as much fluid as I could out of the pan before dropping it. Then - and this was actually more useful thing I did with the Mityvac - I used to drain the old fluid into - by using the Mityvac I could set it up off to the side so I could see it from the driver seat. I setup a hose coming from the transmission cooler line - over to the Mityvac - and then filled up the pan. Turn the truck on for a few seconds - and flush some fluid into the Mityvac. Check the fluid level - and add more. Turn it on again and flush some more fluid - rinse and repeat until you start seeing clean fluid draining into the Mityvac. That way you get ALL of the fluid out of the transmission and replace it with clean new fluid.

Heard a bunch of people saying "you're going to blow up the transmission!!" blah blah blah. Well over 2 years and 20,000 miles or so later - the transmission is doing just fine thank you very much.

You're going to need a few gallons to do the flush / new fluid install the way I describe above ( I think I used up 6 gallons) - but you will get ALL of the fluid out including the fluid that is in the convertor.

Oh yeah - and look around for where to get rid of the old fluid. My local Autozone doesn't take it. I had to get rid of my old fluid at the town hazardous fluid collection day.