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Transmission Fluid Advice


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I just brought my 2015 Sierra to the dealer for an oil change.  I was going to have them do a pan drop and filter change for the transmission for routine maintenance.  (51k miles, original owner). However when I got there they said they’ll typically only do a flush, and really it’s overkill for my truck in it’s current state.

 

After a little discussion, they said they could do a pan drop and filter change but it would be $400+ for labor and parts vs $179 for the flush.  

 

I’m hesitant about a flush, but I was told it will cause no issues.  Seems that a pan drop and filter change on these trucks is the typical service recommendation though.  I’ve thought about doing it myself, but it looks like a real PITA, especially with the filter seal.

 

I was also quoted $150 for a pan drop / filter change by a local AAMCO transmission shop. 

 

Should I just get a flush from the dealership or do it myself?  Or have another shop service it?

 

 

 

 

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51k and original fluid. Oh boy
No question at all pan drop. Filter and fluid. But wait there is more....remove inspect the magnet and clean it then run all extra fuild out. You never get it all with the converter and all the stock lines and coolers. Now replace magnet an filter reinstall pan and fill. But do the fuild reset and a trans relearn.
I do not believe in the flush. Unless there has been a magnet clean off and lower mileage flushes.
Dealer doesn't much care they assume you will just get out of and warranty before trans goes.


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DO NOT back flush that transmission. Buy the PML pan with drain plug and pay AMMCO to do the drop/filter and pan replacement. Next time  you want to do the service do in the driveway. I installed the PML on mine and my local shop charges me $18 to do a drop and fill if I supply the fluid. Same as an oil change. 

 

DO NOT let them use a bulk fluid. Use a quality D6 fluid. Mobil, Valvoline, AMSOIL, Red Line in bottles. 

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Just to ask for my own good. You are all mentioning to not back flush the trans but would pulling the oil cooler line and letting the truck sit and run that out hurt any? I did that on my old truck without any problems and that was done at 100k miles but I didn't have a thermostat like this truck has for the trans.

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I would not do that. It is low power but you are running dry so to say.
I like gp advice. And look at that magnet it will be so covered in shavings it will need to be cleaned off. No sense leaving all that in there. Gm should have added a drain or set exhaust so pan removal is easier. Some times it makes sense to buy the good aftermarket pan so you get drain. Or add a drain. And have cheap trans drains.

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19 minutes ago, Grumpy Bear said:

DO NOT back flush that transmission. Buy the PML pan with drain plug and pay AMMCO to do the drop/filter and pan replacement. Next time  you want to do the service do in the driveway. I installed the PML on mine and my local shop charges me $18 to do a drop and fill if I supply the fluid. Same as an oil change. 

 

DO NOT let them use a bulk fluid. Use a quality D6 fluid. Mobil, Valvoline, AMSOIL, Red Line in bottles. 

For sure.

:)

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8 minutes ago, 1SLOW1500 said:

I would not do that. It is low power but you are running dry so to say.
I like gp advice. And look at that magnet it will be so covered in shavings it will need to be cleaned off. No sense leaving all that in there. Gm should have added a drain or set exhaust so pan removal is easier. Some times it makes sense to buy the good aftermarket pan so you get drain. Or add a drain. And have cheap trans drains.

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I figured I would first unhook the trans cooler line right off the tranny and run a line in a bucket to capture the fluid and keep pouring in fresh fluid at the same time I am pumping the old out. Once it comes out as clean as it is going in I will just snap off the donut flange that is connecting the cat to the muffler as mine is all rusted so I can't unbolt that and would if needed unscrew the bolts holding the exhaust to the header and drop the pan and change the filter and clean up the magnet. Bolt it back together and fill it back up so it's full.

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I just posted about this yesterday in the "Shudder/Vibration Issue" thread, I had the flush done at my GM dealership and it led to issues. They charge $199 for the flush and said it wouldn't lead to issues. I had shudders/vibrations after the flush. Fortunately, they kept my business by dropping the pan, doing a triple flush cleaning to get the old fluid out, replaced the TC, put in the updated fluid, and reprogrammed the tranny to updated settings - all on their dime ($2k). I'm assuming all of that could have been avoided if they just dropped the pan and replaced the filter. These seem to be the most finicky transmissions GM has engineered. I've always had good luck with my previous GM vehicles. Fingers crossed for no issues on yours.

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1 minute ago, kickass audio said:

I figured I would first unhook the trans cooler line right off the tranny and run a line in a bucket to capture the fluid and keep pouring in fresh fluid at the same time I am pumping the old out. Once it comes out as clean as it is going in I will just snap off the donut flange that is connecting the cat to the muffler as mine is all rusted so I can't unbolt that and would if needed unscrew the bolts holding the exhaust to the header and drop the pan and change the filter and clean up the magnet. Bolt it back together and fill it back up so it's full.

Yeah but can’t get it out of the trans cooler that way

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1 minute ago, truckguy82 said:

Yeah but can’t get it out of the trans cooler that way

I didn't mention I was going to take the return line (whichever one that is) at the transmission and hook that up to my bucket. That way the entire system is getting the fluid ran through it. I just hope that I don't get a leak on the quick disconnect. I had messed with the oil cooler line on the radiator and have a small trace of oil around that area now from when I pulled the c-clip and pulled the line out.

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2 minutes ago, diyer2 said:

kickass

This will waste 6 quarts of trans fluid by droping the pan after fluid exchange.

:)

I'm alright with that. I buy the stuff by the box at NAPA when I did it last time. I just buy the filter as an ac delco OEM one from rockauto. The only concern for me is really having the disconnect leak after I take it out and the concern of the adaptive relearn. My old trans supposedly had the relearn as it was a 4l60e and it didn't have a problem and I never had it taken in to a shop to initiate the relearn.

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4 minutes ago, kickass audio said:

I didn't mention I was going to take the return line (whichever one that is) at the transmission and hook that up to my bucket. That way the entire system is getting the fluid ran through it. I just hope that I don't get a leak on the quick disconnect. I had messed with the oil cooler line on the radiator and have a small trace of oil around that area now from when I pulled the c-clip and pulled the line out.

You can’t do that because of the trans thermostat.

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1 minute ago, truckguy82 said:

You can’t do that because of the trans thermostat.

I thought it still had a little bit of a bypass for it like the thermostat for the engine. If that's the case I can just take it around for a drive and get it nice and hot and let it rip.

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