8 Speed Transmission

[Blackcar]

Are there any owners of the 8-speed transmission that are not having problems with them. Especially after TSB for transmission fluid change.

 

[Doubeleive]

I am sure there a zillion of them working perfectly fine

 

[Blackcar]

Thats good to hear.

 

[tuffguy23]

Are there any owners of the 8-speed transmission that are not having problems with them. Especially after TSB for transmission fluid change.

Well, not to jinx myself, but mine seems to to operating generally " normally" for its build date ( NOV 2014 ). Mine is a 2015 Yukon XL Denali. I had a new torque converter under warranty at 86K miles. I do a Mobil1 blue label fluid and filter change about every year. And by "normal" i mean that I accept a occasional clunky or lurchy 1-2 shift operation and an occasional lurchy / abrupt downshift upon highway acceleration as normal characteristics for this transmission. 98% of the time it shifts fine. i currently have 307,200 miles on it.

 

[Blackcar]

So 7years and that mileage changing every year looks to be 43000 miles a year. Did you do flush every year or filter and fill?

 

[B-train]

Have a 2017 Denali that had the shudder at 42k. Flushed per TSB and has been good. Served at 85k and will be again at 125k. Shifts great, occasional clunkyness aside as mentioned. Seems like it likes to be driven semi-agressively (2k - 2500rpm shifts). Drops in each gear flawlessly. Easy Sunday driving will sometimes lead to it not knowing what to do in some moments, but otherwise a joy to drive.

 

[tuffguy23]

So 7years and that mileage changing every year looks to be 43000 miles a year. Did you do flush every year or filter and fill?

so, this December will be 8 years of ownership. So its about 38,500 mi per year. Never used a "flush". I do my own work. Just drop the pan and install new fluid and filter. It has the 158 degree trans cooler thermostat. I did have to also replace the temp sensor harness twice. I consider myself a conservative driver and of course most of my business travel is highway miles.

 

[Blackcar]

Any one come up with a slick way to flush these eight speeds with correct fluid (Mobile one blue) at home with a lift or not.

 

[B-train]

The only way I can think to do it is to pull a return line from the cooler and put into a bucket. Then, pop the fill plug off the trans (passenger side behind heat shield - remove said shield) and put a long section of clear tube up into the engine compartment so you can put a funnel into it to fill it.

If you measured what you took out and replaced with the same, I would think you'd be in the money. I'd still pull the stand pipe plug after a test drive to confirm. This may be my new preferred method after they screwed it up the last time at the dealership.

I hate the new design.......for cryjng out loud GM, just give me a $20 dipstick!