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ATF in 2017 Silverado 1500 6Speed .. vs 2020

ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby OldTrucker [OP] » Nov 20 2020, 1:00pm

I have an issue with 6speed Auto Trans in 2017 1500. This transmission clunks at slowdown through 20 mph. Also stumbles/misses gear at acceleration from coast at 10 -25 mph. Now that its getting colder the behavior clunk at deceleration issue has become less frequent. The stumble/miss gear issue I don't think is going to go away regardless of temperature.

My question is has GM gone to a better fluid with 2020/2021 6 speeds? I have at dealer now and as expected they can't issue to reveal. I had hoped and suggested they put new fluid in it.

Seems like the issue is somewhat temperature/viscosity related. In heat of summer it clunks bad.
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Re: ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby vpasla1 » Nov 20 2020, 1:19pm

It's possible if night be a viscosity thing if it varies with temperatures.

How's many miles on the truck? Have you ever changed the fluid?
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Re: ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby OldTrucker [OP] » Nov 20 2020, 2:22pm

33,000 miles. Never changed. I read where they went to different fluid thats $$. May just be 8 speed.
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Re: ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby Z15 » Nov 20 2020, 2:38pm

That's the 8-sp, Dexron HP. The 6-sp does not use the same fluid, it uses Dexron VI. The main difference being a lower viscosity for Dexron HP.

Remember all the components that go into a new vehicle come from the lowest bid supplier. Just because GM's brand name is on a lubricant does not mean it’s the best there is. It only means its good enough for GM.
GM Dexron HP
"The base stock of old fluid (19355656) has the ability to attract low levels of moisture, which can cause degradation of the coefficient of friction of the fluid. The new fluid (19417577) has a new GTL (Gas to Liquid) base stock that is able to tolerate more moisture. Shuddering transmissions and torque converters have been recovered with the new fluid. New transmission fluid tests have been developed due this issue to prevent it from occurring with new transmission fluids."
Mike

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Re: ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby Delrio » Nov 20 2020, 2:52pm

My '17 did the same thing. The only thing that fixed it was a tuner.

I have a 2020 2500 now and they use the same tranny with some upgrades to handle the HP and Torque. More importantly, I think, they tuned it right. It never searches for a gear like the 6 speed in my '17.

I remember in my '17, before the tune, watching that tach hop around like an easter bunny.
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Re: ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby OldTrucker [OP] » Nov 20 2020, 3:48pm

I wonder if a fluid change would help then. What would be a good fluid? Of course it would be nice if dealer had but doubt thats happening.

I've thought about a tuner but after doing the catch can and range device I'm getting kind of weary of this dance.

Nice truck overall but my previous daily driver '06 1500 was much more enjoyable in terms of drivetrain feedback.
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Re: ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby Z15 » Nov 20 2020, 4:14pm

From AMSOIL

Michael,

Thank you for taking the time to contact AMSOIL with your question.

The AMSOIL ATL covers the DEXRON HP specification, and is recommended for any GM applications that call for this specification. The bulletin appears to be discussing the GM branded fluid having moisture issues and being upgraded, however, that information does not apply to the AMSOIL lubricant.


Note when I had the GM dealer change out mine on my 2017 they needed 18 qts to complete the change over as there is always going to be some waste as changing ATF is not as precise a task as an oil change. Cannot say if the clunking will stop. My 8-sp does it occasionally. Note-The AMSOIL fluid is 100% Synthetic, GM is not.
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Re: ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby OldTrucker [OP] » Nov 21 2020, 12:08pm

The clunking is not happening in this cooler weather. They could not get it to do it as they drove it twice after keeping it over night. They Drove it 75 miles.

I did not notice it coming home as the trans temp got up to 165degrees. They gave me sheet to record environment when it happened and bring it back it if and when I could get some meaningful data.

It happens religiously from when its hot but thats not now.

The shift logic in these drivetrains is poor. Irritating at times, slow to get up and run.

It runs great when you get on it. The amount of power difference from this 5.3l compared to my tired 160,000 mile 5.3 with 4 speed is considerable. This 2017 is apparantly now getting broken in and cooler intake air helps.
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Re: ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby Delrio » Nov 21 2020, 4:07pm

OldTrucker wrote:I wonder if a fluid change would help then. What would be a good fluid? Of course it would be nice if dealer had but doubt thats happening.

I've thought about a tuner but after doing the catch can and range device I'm getting kind of weary of this dance.

Nice truck overall but my previous daily driver '06 1500 was much more enjoyable in terms of drivetrain feedback.


Yea, I hear you. Sorry to say... but They GM really throttled these model years in so many ways. Between the trany not being able to decide on a gear, the cylinder shut-off, the flexing gas pedal (poor mount to firewall), the horrible tuning... Was not fun to drive. For the discerning driver, you have to tune it, catch can it, and stop the flex in the gas pedal (paint stick mod - google it). With all these mods - loved it. Took all those mods off before trading it in and was reminded how crappy they drive stock...

by the way - The range device is great... (currently have it on wifes car) but doesnt address the trans tuning in these trucks.
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Re: ATF in 2017 Silverado 1500 6Speed .. vs 2020

Postby OldTrucker [OP] » Nov 22 2020, 3:15pm

If you get a tune does it also tune out the cylinder shutoff so that I could sell my range device to offset some of the tune cost?
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