5.3 8 speed questions

Craig_K · May 19, 2016

I will soon be purchasing a 2016 Silverado LTZ 5.3 with the 8 speed automatic. I have heard from some that they get worse gas mileage than the 6 speed... Is there any truth to that? I have read a few threads about this but could not find any recent ones (the ones I found were all from 2015). Has there been any changes to make the mpg better? I want to make sure I know what I'm getting myself into before dropping that kind of money. Thanks!

Tattooo · May 19, 2016

I had a AT 2014 5.3 6 speed and now have a AT 2016 5.3 8 speed and I dont see any difference.

Craig_K · May 19, 2016

That is exactly what I wanted to hear! Thanks Tattooo

fondupot · May 19, 2016

That is exactly what I wanted to hear! Thanks Tattooo

For whatever reason, yes. the EPA rated the 5.3 with 8 speeds 1 less MPG than 5.3 with 6 speeds.

But in real world driving you probably won't notice a difference as Tattooo says.

The Mad Veteran · May 19, 2016

For whatever reason, yes. the EPA rated the 5.3 with 8 speeds 1 less MPG than 5.3 with 6 speeds.

But in real world driving you probably won't notice a difference as Tattooo says.

I just noticed the difference. That's really weird since you would have the lower rpm would help with this.

mookdoc6 · May 19, 2016

Real world driver exact setup 5.3 CC 2wd with 8speed 3.42 Rear

It actually has different EPA ratings than 6speed. The final gear is actually lower than final of 8speed I believe but not by much. So it's actually geared better for towing/shifting up grades....taking off etc.

Look, right now I have 1800 miles on the thing. I am averaging 21.2 mpg's and the 8speed is freaking nice! The guy who parks next to me has brand new FORD 5.0 V8 and drives same route I do with more freeway time and is averaging 17.something? I told him dude been driving work trucks my whole life and FORD simply does not compete with GM on powertrain

mookdoc6 · May 19, 2016

I have absolutely nothing to complain about.....Love the setup....5.3 8speed!

It acts funny for the first 1000 miles or so and poof....it's gone.....no rolling off the gears just instant bliss brother!

brosse01 · May 19, 2016

I just took delivery of my new 2016 Sierra SLT 4X4 Crew Cab 5.3L with 8 speed a few days ago. 120 miles so far. I am experiencing a transmission shift jolt when coming to a stop. It is probably the trans shifting from 2nd to 1st. It is pretty harse. Seems to happen every stop. Seems the up shifts are a little more noticable than I would expect. I hope there is a calibration fix for this soon.

mookdoc6 · May 19, 2016

Keep drivinig it normally like you do and after 1000.00 + miles it will all be gone! Trust me

redwngr · May 19, 2016

I just took delivery of my new 2016 Sierra SLT 4X4 Crew Cab 5.3L with 8 speed a few days ago. 120 miles so far. I am experiencing a transmission shift jolt when coming to a stop. It is probably the trans shifting from 2nd to 1st. It is pretty harse. Seems to happen every stop. Seems the up shifts are a little more noticable than I would expect. I hope there is a calibration fix for this soon.

Keep drivinig it normally like you do and after 1000.00 + miles it will all be gone! Trust me

Mine still does it occasionally -- but it's not as frequent or harsh as it used to be. Currently at about 12,000 miles.

I'm currently 'testing' the 'normal mode grade braking' disable that is being discussed in another thread (last I checked in, that thread is still primarily discussing 6 speed -- but the 8 speed can be disabled using the same technique)

intimidator01238 · May 19, 2016

My uncle brought his 2016 6.2 8 speed in yesterday for its first service and complained about the jerky erratic shifting. Both his and my truck were both built in December so not long ago. He brought the bulletin with him about the torque converter replacement but they didn't do anything with that at this time. What they did find is there was some update supposedly to the transmission. I'm not exactly sure if it was a tcm update or what. The paperwork didn't call out anything specific. They said right now try it with this update and if you are feeling any shuddering still to bring it back and we'll do the torque converter update. I'll be bringing mine for its first service soon too and I'll try to find out more details about this. I'm hoping this corrects some of the whacky shifting I sometimes experience. It's fairly smooth most of the time and then it seems to act totally different at other times.

InertiaFaze · May 20, 2016

I just took delivery of my new 2016 Sierra SLT 4X4 Crew Cab 5.3L with 8 speed a few days ago. 120 miles so far. I am experiencing a transmission shift jolt when coming to a stop. It is probably the trans shifting from 2nd to 1st. It is pretty harse. Seems to happen every stop. Seems the up shifts are a little more noticable than I would expect. I hope there is a calibration fix for this soon.

Normally the trans shifts from 3rd to 1st instead of from 2nd to 1st, unless of course your driving very low speed and haven't shifted yet to 3rd. And I read a bulletin that describes how to speed up the adapting process for the 3rd to 1st shift which involved driving in 6th gear (M6) at about 40 mph and light on the pedal.

kp52 · May 20, 2016

Not to get too far off topic but what dictates the 5.3 8 speed in the GMCs? I recently picked up a new (4/16 build date) SLT 5.3 4x4 CC with 3.42s and it has the 6 speed. According to the GMC site CC SLT the 8 speed is standard..

Was there some restrictions on the 8 speed for a while or do only certain combinations get them?

Not a big deal, I'm OK with the 6 speed (very used to the one in my old '15 Silverado), was just wondering..

FADEC · May 20, 2016

Not to get too far off topic but what dictates the 5.3 8 speed in the GMCs? I recently picked up a new (4/16 build date) SLT 5.3 4x4 CC with 3.42s and it has the 6 speed. According to the GMC site CC SLT the 8 speed is standard..

Was there some restrictions on the 8 speed for a while or do only certain combinations get them?

Not a big deal, I'm OK with the 6 speed (very used to the one in my old '15 Silverado), was just wondering..

I have the same truck as you but built 12/15. My 8 speed was standard equipment with the SLT CC. Not sure why GM cut it out on trucks like yours. I wonder if the Chevy LTZ got it cut as well.

kp52 · May 20, 2016

I have the same truck as you but built 12/15. My 8 speed was standard equipment with the SLT CC. Not sure why GM cut it out on trucks like yours. I wonder if the Chevy LTZ got it cut as well.

Most likely they had a restriction on them for a while, I just looked at a couple CC 4x4 SLTs at a local dealer that just came in and they had 6 speeds as well but older stock had 8 speeds. Like I said its not a big deal to me, I didnt expect the 8 speed with the 5.3 so I wasn't disappointed but I'm sure someone will get upset about it