TRANSMISSION OIL CHANGE

[MRV1]

After how many miles/years should the transmission gear oil be changed?

 

[StormTrooprSubZ71]

What year and mileage do you have on it? 1st owner?

 

[B-train]

Depending on the driving style and use it gets makes a difference. If it's mostly highway and low load use, then I do 40 to 50k. If it's more spirited driving, hill or mountain roads, city, trailering etc I would stick to 30k intervals

 

[clogan2]

I followed the schedule in the owners manual: 100,000 miles.

 

[OR VietVet]

I am of the group that uses the 30k or 50k miles interval and for the same reason. Hell, I change my Mobil 1 full synthetic every 5k or less. As the mood strikes me.

 

[strutaeng]

This is the 6L80/90, right?

I think 50k on that unit is recommended? Maybe as little as 25k if you haven't disabled the AFM/DoD and do heavy towing or a lot of city driving?...see the 6L80e thread from @NickTransmissions for more info.

On the old 4Lxx and earlier models there's this idea that changing your transmission fluid at high mileage will cause it to start slipping because the "old ATF has 'grit' to help the clutches engage." I've heard even reputable mechanics mentioned this like it's the Gospel. I certainly believed this myself. As far as I know that is false, and is an old-wives tale. This should be like a PSA.

There's absolutely no way a friction particle that got abraded away and is floating around in the lubrication circuit can do this. The friction material is bonded to the backing substrate. Keyword: bonded. After it falls off it doesn't do anything. Not to mention all the grit would cause damage to bushings, bearings, valve body valves. Yuk. The proof is converter failure of a 6L80e causing extreme scoring and damage to the pump body. :-(

 

[Big Mama]

I did a complete flush at 100k. My trans guy asked if I was having any issues before he would do it.

 

[Seamus]

Every 30-50K depending on use.

 

[BADRIDES]

100,000 for everyday driving and 30-50,000 if you pull with it

 

[tom3]

I'm doing mine at 30k so I can see what's in the bottom of the pan. I have noticed that when I check the fluid level when I wipe off the stick I get some black stuff on the rag. The actual ATF still looks and smells fine. I really don't like the way that torque converter slips so much. I really wonder why GM went with that?