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8 speed fluid and filter change


tlaw91
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On 12/9/2020 at 9:22 PM, tlaw91 said:

HEY I GOT A POST PERMANENTLY PINNED ON HERE NO FREAKIN WAY

maybe I should do more of these ‘how to do common things on GM cars’ things

Like your damn battery cables. You all need battery cables emoji23.png


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Please do !  This one was very helpful.  

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On 12/9/2020 at 8:22 PM, tlaw91 said:

HEY I GOT A POST PERMANENTLY PINNED ON HERE NO FREAKIN WAY

maybe I should do more of these ‘how to do common things on GM cars’ things

Like your damn battery cables. You all need battery cables emoji23.png


Sent from my iPhone using Tapatalk

If you do, please post them in the "Technical/Advanced: How To:" Section. This post will wind up there

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  • 4 months later...

Question for you all.  If I drain, change filter, and refill with the Mobil 1 HP LV fluid recommended for my 2018 Colorado 8-speed transmission, will I run into any trouble with the new fluid and old fluid from a compatibility perspective?  I am leery of having anyone do a flush, and I don't want to unhook lines and risk running the pump dry on my own.  But I am worried about fluid compatibility.  The new fluid is supposed to be compatible with the Dexron VI.  I am probably being paranoid and over-thinking this.

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5 hours ago, TVR123 said:

Question for you all.  If I drain, change filter, and refill with the Mobil 1 HP LV fluid recommended for my 2018 Colorado 8-speed transmission, will I run into any trouble with the new fluid and old fluid from a compatibility perspective?  I am leery of having anyone do a flush, and I don't want to unhook lines and risk running the pump dry on my own.  But I am worried about fluid compatibility.  The new fluid is supposed to be compatible with the Dexron VI.  I am probably being paranoid and over-thinking this.

No issues at all.  Just that you will not get the full benefit of the fluid since it will mix with the old.  That is why the dealer does a complete fluid exchange.  To make sure the transmission system has as close to 100% new fluid as possible.

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What does everyone think about the approach to getting at most of the fluid through disconnecting the lines and letting the pump push out the old fluid in the TC and cooler circuit?  Shut down when fluid begins to show any evidence of a pulse.  Then drop pan and change filter, clean up magnets, etc.  Then refill and start, allowing some to push out of the cooler lines until a good color change.  Then connect everything and check fluid level.  Terrible idea risking running pump dry or okay if cautious?

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I followed tlaw91’s procedure and a YouTube video and changed my 8l90’s filter and fluid today.

 

I had dealer do the first time at 45k.  34k later it’s my turn.

 

I bought a fluid extractor to suck most out of the pan first.

 

The most time consuming step was getting the darn heat shield removed.  The rest was easy.  I took my time - like really slow and it took 2.5 hours.

 

I have a scan tool (ScanGauge II) to measure fluid temp-  needs to be between 95-113 degrees.

 

Did not have to disconnect solenoids (like tlaw91 or bend the exhaust cross over.  I was able to easily slide pan out by turning front side (facing front of car) towards passenger side.

 

Filled with 8 qts and about 1/2 -3/4 qt drained out during level check.

 

magnets were dirty, fluid was dark, didn’t smell bad .  Pan was a little dirty.

 

You can do it on the driveway, just take your time.

 

I plan to suck out pan and refill in a few weeks again to refresh more fluid.  Then going forward, suck and fill each year.

 

 

0C7C74E5-D6A9-47DF-9DCA-D3FF4466E782.jpeg

Edited by SuperOldSchool
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On 4/20/2021 at 11:07 AM, TVR123 said:

What does everyone think about the approach to getting at most of the fluid through disconnecting the lines and letting the pump push out the old fluid in the TC and cooler circuit?  Shut down when fluid begins to show any evidence of a pulse.  Then drop pan and change filter, clean up magnets, etc.  Then refill and start, allowing some to push out of the cooler lines until a good color change.  Then connect everything and check fluid level.  Terrible idea risking running pump dry or okay if cautious?

No issues at all doing it this way.  Just have someone in the truck ready to turn it off once the fluid coming out starts to slow down or "spit" so to speak.  I did a few vehicles this way with no issues.  It is the best way for DYI to get a good fluid exchange.

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On 4/24/2021 at 5:50 PM, SuperOldSchool said:

I followed tlaw91’s procedure and a YouTube video and changed my 8l90’s filter and fluid today.

 

I had dealer do the first time at 45k.  34k later it’s my turn.

 

I bought a fluid extractor to suck most out of the pan first.

 

The most time consuming step was getting the darn heat shield removed.  The rest was easy.  I took my time - like really slow and it took 2.5 hours.

 

I have a scan tool (ScanGauge II) to measure fluid temp-  needs to be between 95-113 degrees.

 

Did not have to disconnect solenoids (like tlaw91 or bend the exhaust cross over.  I was able to easily slide pan out by turning front side (facing front of car) towards passenger side.

 

Filled with 8 qts and about 1/2 -3/4 qt drained out during level check.

 

magnets were dirty, fluid was dark, didn’t smell bad .  Pan was a little dirty.

 

You can do it on the driveway, just take your time.

 

I plan to suck out pan and refill in a few weeks again to refresh more fluid.  Then going forward, suck and fill each year.

 

 

0C7C74E5-D6A9-47DF-9DCA-D3FF4466E782.jpeg


 

Extracted and replaced another 5qts today- total 13 fresh.   Should be good for a while....

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  • 2 months later...
  • 2 weeks later...

Got our 8 speed drained & changed with the new fluid at 80K yesterday, fluid / filter and labor was $265 plus tax at Mr. Transmission near my house.  The owner test drove it and said is shuddered once on him, then no more.  No shudders for me.  The owner has a 2019 Silveraddo 6speed he said GM replaced 2 times now.  His thoughts, the 8 has the shudder problem but it's not breaking like the 6 speeds he sees including his . 

Edited by Srode1
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  • 2 months later...
14 hours ago, Jay Fisher said:

I had my trans fluis flushed today and seems on the 20 mile trip home it was smooth  and shifted well.

Curious how many miles since the last flush or if the first one how many miles on the truck? 

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