GM 6L80 Transmission Information Thread

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Power_Dr

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I have a question about the fluid exchange on a 6L80E. I would like to do a fluid exchange myself after I drop the pan and replace the filter. My question is, with the transmission thermostat bypass valve, how do you get fluid to be pumped out of the transmission via the cooler line if the transmission is not up to temp? If the bypass thermostat is not allowing the fluid to get out of the transmission?
 

Power_Dr

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Nicki, what do think about mixing GM non-synthetic with synthetic transmission fluid? I was going to drop the pan and do a filter and fluid change. I was going to put back in synthetic GM fluid, but not exchange all the fluid so the synthetic would mix with the original non-synthetic.
 
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NickTransmissions

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Nick, what do think about mixing GM non-synthetic with synthetic transmission fluid? I was going to drop the pan and do a filter and fluid change. I was going to put back in synthetic GM fluid, but not exchange all the fluid so the synthetic would mix with the original non-synthetic.
My name is "Nick" not Nicki.

You should have Dex 6 full synthetic in your trans and only use Dex 6 for any flushes or refills after you service it.

See my first post for the link to installation and fill/check level procedures - it will give you all the info you need to refill the trans and check the fluid level.

Note - You do no need to do a "fast adapt" if just replacing the filter and adding new fluid.
 
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Power_Dr

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My name is "Nick" not Nicki.

You should have Dex 6 full synthetic in your trans and only use Dex 6 for any flushes or refills after you service it.

See my first post for the link to installation and fill/check level procedures - it will give you all the info you need to refill the trans and check the fluid level.

Note - You do no need to do a "fast adapt" if just replacing the filter and adding new fluid.


I am sorry about the name, I thought I had typed Nick and I didn't proof read, my fault I apologize. So on my 2019 Yukon 6le80 has the full synthetic from the factory?
 
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NickTransmissions

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I am sorry about the name, I thought I had typed Nick and I didn't proof read, my fault I apologize. So on my 2019 Yukon 6le80 has the full synthetic from the factory?
No worries and yes, you already have full synthetic from the factory. GM went to full synthetic over conventional for a host of reasons - the first post has a link to an ATRA handout that provides info on the reason for the switch, if you're interested.
 

Power_Dr

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No worries and yes, you already have full synthetic from the factory. GM went to full synthetic over conventional for a host of reasons - the first post has a link to an ATRA handout that provides info on the reason for the switch, if you're interested.

I was looking at this fluid 1686940948530.png that I thought was what I wanted to put in, it doesn't say synthetic, but then I see this 1686940982597.png which says full synthetic. Thank you for your information, I just want to put in whatever would be the best for my yukon. thank you.
 

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So with those two gallon jugs that I just posted, why does only the one say Full Synthetic?
 

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