2014 6L80 transmission fluid change

fiziksgeek · November 25, 2016

Hey guys,

I changed the fluid in my front and rear diffs and transfer case a couple weeks ago ( converting to all Amsoil fluids), still want to find time to change out the transmission fluid before the weather gets too cold and have a couple questions.

I wanted to drop the pan, change the filter, and flush the system by disconnecting the output from the transmission cooler. I read that starting in 2014 the flow to the cooler is thermostatically controlled. Can someone confirm that? If so, what is the temp setting? Is there way to bypass the switch for service? Or do you have to heat the fluid? if so, how?

Z45 · November 25, 2016

I had my 2015 8-sp changed over to AMSOIL the past spring. I was told as well there is a thermostat in the pan but I don't know anything else about it. The GMC dealer charges a flat rate of $89 to service the trans. I provided the fluid, they used 16 qts on mine.

fiziksgeek · November 25, 2016

I had my 2015 8-sp changed over to AMSOIL the past spring. I was told as well there is a thermostat in the pan but I don't know anything else about it. The GMC dealer charges a flat rate of $89 to service the trans. I provided the fluid, they used 16 qts on mine.

Thanks for the reply. Maybe I'll investigate the cost to have the dealer do it, have to take it in for a recall anyway. Though I would really like to do it myself. First, the service shop at the dealer I bought from is slow as could be (never get out of there in less than 1.5 hours for a oil change when I have an appointment), , second, I don't fully trust someone else to do it...unless I can watch...and these days most places don't let you in the garage!

One more question for the crowd, The output of the transmission cooler is right under the radiator line the goes to the overflow tank, is that correct? Looks like ~1/2" tubing should fit right in there?

fiziksgeek · November 26, 2016

For reference, here is the old thread I found where one person indicated that the flow to the cooler was thermostatically controlled.

http://www.gm-trucks.com/forums/topic/165195-2014-transmission-flush/

fiziksgeek · November 27, 2016

Well, for anyone looking for information. On the passenger side, the two larger lines are for the oil cooler, The smaller line between the two is the input to the transmission cooler, the output is on the drivers side. I had run a couple of errands before starting the job, and the transmission was reading ~140 when I started the job. Transmission fluid flowed freely through the lines to the cooler, so either there is no thermostatic control, or I was above the temperature set point...

Eddie 70 · December 4, 2016

I am getting ready to do this same job on my 14. Were you able to drop the pan and get the filter out? I have seen a video where the guy had to loosen the exhaust at the manifolds to get the pan to clear the crossover pipe. How many quarts did you use? Did you start the truck during the change to empty the converter?

Thanks for any help.