2020 10 speed trans service question

[johnnyquick]

Gents, I bit the bullet on this 2020 1500 and decided to do the trans filter and fluid service at home after watching 1 really good video on youtube and one that was just okay.

Jacked her up took off front wheels,  safety stands etc pulled fender liners, out Pulled a few heat shields off, popped 3 02 sensors out, left passenger downstream one in place as lead is long enough.

Cussed a few hundred times trying to get inside passenger manifold bolt out, and got exhaust dropped so I could access and drop pan and fluid.

All went well, til I started getting things cleaned up before reassembly, as I emptied my waste oil into some jugs I had laying around for this task, I filled one to 4 qts exactly and another one I put 24 ounces into.

That is all that came out of it, I have owned it since new, (26 miles) and it has never leaked a drop, nor has anyone ever touched the trans for service etc, I had 2 services done at the dealer both long ago like around the 10k mark on the odo.

Never any issue wityh shifting etc, other than typical slow assed GM shifts.

Everywhere I read says it takes 8.1 qts for this service, tomorrow I will follow all procedures and get it up to temp etc and fill her up but tonight I am questioning WTF?

Other than roll with it after the fill up what do you think?

[Bikerjon]

1 hour ago, johnnyquick said:

Gents, I bit the bullet on this 2020 1500 and decided to do the trans filter and fluid service at home after watching 1 really good video on youtube and one that was just okay.

Jacked her up took off front wheels,  safety stands etc pulled fender liners, out Pulled a few heat shields off, popped 3 02 sensors out, left passenger downstream one in place as lead is long enough.

Cussed a few hundred times trying to get inside passenger manifold bolt out, and got exhaust dropped so I could access and drop pan and fluid.

All went well, til I started getting things cleaned up before reassembly, as I emptied my waste oil into some jugs I had laying around for this task, I filled one to 4 qts exactly and another one I put 24 ounces into.

That is all that came out of it, I have owned it since new, (26 miles) and it has never leaked a drop, nor has anyone ever touched the trans for service etc, I had 2 services done at the dealer both long ago like around the 10k mark on the odo.

Never any issue wityh shifting etc, other than typical slow assed GM shifts.

Everywhere I read says it takes 8.1 qts for this service, tomorrow I will follow all procedures and get it up to temp etc and fill her up but tonight I am questioning WTF?

Other than roll with it after the fill up what do you think?

Is there a drain plug on the torque converter? The cooler must retain some fluid.

[KARNUT]

8 hours ago, johnnyquick said:

Gents, I bit the bullet on this 2020 1500 and decided to do the trans filter and fluid service at home after watching 1 really good video on youtube and one that was just okay.

Jacked her up took off front wheels,  safety stands etc pulled fender liners, out Pulled a few heat shields off, popped 3 02 sensors out, left passenger downstream one in place as lead is long enough.

Cussed a few hundred times trying to get inside passenger manifold bolt out, and got exhaust dropped so I could access and drop pan and fluid.

All went well, til I started getting things cleaned up before reassembly, as I emptied my waste oil into some jugs I had laying around for this task, I filled one to 4 qts exactly and another one I put 24 ounces into.

That is all that came out of it, I have owned it since new, (26 miles) and it has never leaked a drop, nor has anyone ever touched the trans for service etc, I had 2 services done at the dealer both long ago like around the 10k mark on the odo.

Never any issue wityh shifting etc, other than typical slow assed GM shifts.

Everywhere I read says it takes 8.1 qts for this service, tomorrow I will follow all procedures and get it up to temp etc and fill her up but tonight I am questioning WTF?

Other than roll with it after the fill up what do you think?

Just out of curiosity. Is there no way to do several drain and fills to change the fluid? I’ve always done it that way no matter the brand. I’ve never changed the filter. If it’s getting restricted it’s a goner anyway. I can’t believe the process for dropping the transmission pan. Unbelievable.

[johnnyquick]

1 minute ago, KARNUT said:

Just out of curiosity. Is there no way to do several drain and fills to change the fluid? I’ve always done it that way no matter the brand. I’ve never changed the filter. If it’s getting restricted it’s a goner anyway. I can’t believe the process for dropping the transmission pan. Unbelievable.

Yes it is a real BIOTCH, I am adding a B&M drain plug to it as well as heat wrapping the exhaust on both sides as well as along the bottom pipe that cuts across about and inch and a half under the trans pan.

My plan is to run the added new fluid for a few days then drain again via the new plug and then switch to Amsoil for the next run and then again in Spring which SHOULD have my fluid in damn good shape, I may even do the Valve Body upgrade at that time.

7 hours ago, Bikerjon said:

Is there a drain plug on the torque converter? The cooler must retain some fluid.

I will look and see if any is accessible to me.

 

7 hours ago, Bikerjon said:

Is there a drain plug on the torque converter? The cooler must retain some fluid.

 

[johnnyquick]

All is well that ends well, filled it with what came out exactly and the B&M drain plug kit is in.

I was going to torque the nut to the spec'd to the manufacturers 25# but it destroyed the nylon washer before that number came close, so I replaced it with a copper crush washer. (No leaks)

I have enough of of the Delco ULV to drain and refill again so I will do that and should be ALL new fluid, which then I will dump that after a few miles and sub it with the Amsoil and forget it til spring and then dump it ALL and do the Valve body upgrade kit from Next Gen drivetrain and refill with Amsoil again and then gettting the trans tuned at a local shop that has done a few of them with great results.

Any way that is it.

Cheers

[Black02Silverado]

For a pan drop that sounds to me about right for the most part.  The way to tell would have been to check the fluid level before you started.  At the recommended temp pull the side plug and it should have just barely trickled out.

[SIXFOUR]

Would that be operating temp?

Is the hex plug metric? And location is on what side of the transmission? That pan removal would be too much for me.

[johnnyquick]

3 hours ago, SIXFOUR said:

Would that be operating temp?

Is the hex plug metric? And location is on what side of the transmission? That pan removal would be too much for me.

A large allen head (metric)  but if you want to use a rachet you will need to remove the front drive shaft (if your truck is 4wd of course).

Otherwise as I did use a allen wrench and a box end slipped over it to get leverage enough to break it loose.

Drivers side, you will clearly see it on side of trans.

Get it up to 180 on dash indicator by power braking it for 10 seconds on and 10 seconds off til you get there, leave it run as you open plug to see if any trickles out, fill it until it does but just a drip not any more.

Manuals say like 170-175 but I was wanting time to slip on coveralls real quick and jump under there.

Fluid is damn hot so be careful.

 

Edited October 24, 2025 by johnnyquick

[johnnyquick]

On 10/20/2025 at 8:18 AM, Black02Silverado said:

For a pan drop that sounds to me about right for the most part.  The way to tell would have been to check the fluid level before you started.  At the recommended temp pull the side plug and it should have just barely trickled out.

Sooooo, I posted above that I added just what I took out and ran with that 
HOWEVER after I got a helper to pump the fluid while I layed under it ad checked the level and held hose in fill hole, I had it up to 180 degrees pulled plug (truck level) and no fluid, so added 2 more quarts and still had no fluid coming out. 

Put plug in, got out from under and rechecked trans temp, ran it up to 180 again and dropped under and pulled plug STILL NO FLUID so added another full quart (8 quarts now) and finally got fluid coming out as the books and videos show.

Trans has never been touched, I am amazed that it held together at all with only 4 quarts and 28 ounces coming out of it, B*ST*RDS at GM !

I have towed my 24' car hauler all over the rockies and Arizona in 119 degree heat with it factory low on fluid.

So I am doing as posted and draining this next week and putting Amsoil in it and doing upgrade of valve body in the spring.

I would check your trans fluid levels ASAP if you have not already.

Cheers

 

[SIXFOUR]

On 10/23/2025 at 9:53 PM, johnnyquick said:

Sooooo, I posted above that I added just what I took out and ran with that 
HOWEVER after I got a helper to pump the fluid while I layed under it ad checked the level and held hose in fill hole, I had it up to 180 degrees pulled plug (truck level) and no fluid, so added 2 more quarts and still had no fluid coming out. 

Put plug in, got out from under and rechecked trans temp, ran it up to 180 again and dropped under and pulled plug STILL NO FLUID so added another full quart (8 quarts now) and finally got fluid coming out as the books and videos show.

Trans has never been touched, I am amazed that it held together at all with only 4 quarts and 28 ounces coming out of it, B*ST*RDS at GM !

I have towed my 24' car hauler all over the rockies and Arizona in 119 degree heat with it factory low on fluid.

So I am doing as posted and draining this next week and putting Amsoil in it and doing upgrade of valve body in the spring.

I would check your trans fluid levels ASAP if you have not already.

Cheers

 

Dammit,  now I'm spooked. I will be checking ASAP.

IF Anyone else is checking the fluid level on their 10 speed transmission,  let everyone know what you find, and if you have to add any, how much. We would like to know.