6L80 transmission service?

[Chebby]

My new-to-me Yukon XL 1500 doesn’t show any service records for the transmission. Supposing it has never been serviced (fluid/filter or flush), would you start now at 128k miles? 
 

i am leaning toward doing a filter swap and replacing a few quarts at a time due to the mileage. Or do you think the full flush would be better?

[davester]

I would change all the fluids/filters (coolant, brake, power steering, transmission, transfer case, front & rear diffs, and engine oil), unless there was paperwork indicated they had been done recently.  I'm not a fan of transmission flushes, but that's just me.

[swathdiver]

4 hours ago, Chebby said:

My new-to-me Yukon XL 1500 doesn’t show any service records for the transmission. Supposing it has never been serviced (fluid/filter or flush), would you start now at 128k miles? 
 

i am leaning toward doing a filter swap and replacing a few quarts at a time due to the mileage. Or do you think the full flush would be better?

I've done the fluid exchange twice on mine with no ill effects.  First at 117K or so and then at 153K.  The fluid was pretty wore out so from now on it will get done every 36K or so.  Sent off a sample to BlackStone Labs for analysis.  I'll drop the pan next time, still has original filter.  What year is this one?

[elcamino]

When you buy a vehicle YOU OWN IT, NOT GM. GM put just enough thought into it to get it through warranty. They don't own it and once past the ever shrinking warranty, they could care less. They make MONEY not vehicles.

Be your own advocate.         No one else will.  Change your fluids.  ATF like engine oil is built with consumables that are depleted over time. Its not made to last forever despite what some may like to believe.

[Chebby]

3 hours ago, swathdiver said:

I've done the fluid exchange twice on mine with no ill effects.  First at 117K or so and then at 153K.  The fluid was pretty wore out so from now on it will get done every 36K or so.  Sent off a sample to BlackStone Labs for analysis.  I'll drop the pan next time, still has original filter.  What year is this one?

2012 Yukon XL 1500 SLT

 

Fluid exchange...is that a flush and fill?

Edited May 26, 2020 by Chebby

[Chebby]

7 hours ago, davester said:

I would change all the fluids/filters (coolant, brake, power steering, transmission, transfer case, front & rear diffs, and engine oil), unless there was paperwork indicated they had been done recently.  I'm not a fan of transmission flushes, but that's just me.

 

Yeah. I’m doing that. I’m just asking if due to the high mileage I should just drop the pan and change a few quarts at a time or if a full flush would be better. 

[diyer2]

Two choices IMO.

Do a pan drop and filter change. About 6 quarts replaced.

Then buy this https://www.amazon.com/gp/product/B0002AJR8E/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

Remove about 6 quarts through trans filler tube and replace any time you want.

This is what I did on my 2012 Sierra. 

 

Drop pan and filter replace fluid.

Do an exchange, not a flush.

Don't like flushes.

 

[swathdiver]

16 minutes ago, Chebby said:

2012 Yukon XL 1500 SLT

 

Fluid exchange...is that a flush and fill?

The first time I took it to the dealer and they exchanged the fluid with the TransFlow machine.  The machine does a flow test on the transmission cooler and lines and then lets the transmission's pump do the work of removing the old fluid and introducing the new fluid into the system.  The second time I did it at home, took off the top line from the transmission and let it flow into a bucket, then added fluid through the dipstick tube.  Again, the transmission's pump did the work.

 

Decide whether or not you want to turn off AFM and either way, I recommend that you get the truck tuned by BlackBear Performance.  Not to go faster but for improved transmission performance.  Get yourself a Tech-2 so you can properly diagnose and work on your truck too.  After the fluid is changed, you can reset the internal transmission oil life meter with it.

 

If this is a 4x4, do you have a single speed transfer case or a 2-speed TC?  Does it have RPOs K5L, KNP and KC4?

[Chebby]

35 minutes ago, swathdiver said:

The first time I took it to the dealer and they exchanged the fluid with the TransFlow machine.  The machine does a flow test on the transmission cooler and lines and then lets the transmission's pump do the work of removing the old fluid and introducing the new fluid into the system.  The second time I did it at home, took off the top line from the transmission and let it flow into a bucket, then added fluid through the dipstick tube.  Again, the transmission's pump did the work.

 

Decide whether or not you want to turn off AFM and either way, I recommend that you get the truck tuned by BlackBear Performance.  Not to go faster but for improved transmission performance.  Get yourself a Tech-2 so you can properly diagnose and work on your truck too.  After the fluid is changed, you can reset the internal transmission oil life meter with it.

 

If this is a 4x4, do you have a single speed transfer case or a 2-speed TC?  Does it have RPOs K5L, KNP and KC4?

Two speed transfer case

[chem_man]

I concur with diyer2 - pan drop, change filter, and refill. 

 

I would also consider getting a Dorman transmission oil pan with a drain plug if the factory pan does not have one.  It makes future fluid changes much easier as I don't use a fluid extractor.

 

Then drive around a few hundred miles, drain the fluid and replace with fresh and you'll have enough fresh fluid mixed in to go for a year or two before needing to do another drain and fill.

[swathdiver]

3 minutes ago, Chebby said:

Two speed transfer case

Ok, if you have those RPO codes you're good for maximum towing, 8,000 pounds.

[intheburbs]

The only time my two trucks cast a shadow on dealer service bay floors is for a trans flush.  I do it on both, religiously, every 50k miles.  Suburban just rolled 200k miles, still runs perfectly and is all-original.

[carnau]

Ok so everyone has there own experiences with transmission flushs and filter exchanges. I hear horror stories all the time about how people think when they change the fluid or the pan that the transmission begins to have problems. BUT!!! I am going to tell you about my experiences and then I will give you my advice.

 

I have worked at a GM dealership for the Last 20 years and have worked on vehicles even longer. I have done more flush and fills and filter exchanges than I can count. I have watched people do more exchanges and fills than I can count. In those 20 years, I have never seen a transmission come into the dealership without a transmission problem, get a service and come back with an Issue. 

 

BUT!!!! (second but) Most of the time people will come in to the dealership and request a transmission service because they have an "Issue". Once you have an issue... The service will not fix it.

 

Now, For my advice. If you don't have a problem with your transmission. Don't be afraid to change the fluid and filter. I always recommend it every 75k miles. Also, Heat is major cause of transmission failures. Every transmission service we do, every transmission rebuild or even new install we add Lubeguard ( https://amzn.to/36v00A0 ) It is a friction modifier that will help reduce heat.

 

On my personal vehicles I install a larger cooler. But that's only because they get abused on my farm and it doesn't cost me a lot to do it since I do all the repairs myself.

 

The only other thing I would recommend is a reusable trans pan gasket. Just because I think it is a cleaner install, and if you ever go back into it you will not need to replace the gasket again.

The gasket that comes on it is actually a reusable one, But with 120k miles and it only costing $14... I would replace it personally. ( GM Pan Gasket) https://amzn.to/2XurUrG

 

Just my opinion.

[Chebby]

8 hours ago, swathdiver said:

Ok, if you have those RPO codes you're good for maximum towing, 8,000 pounds.

Looks like I do! 

[Black02Silverado]

If it was mine, I would do a fluid exchange along with a pan drop and filter change.  No problem.  I have done several on GM vehicles with over 100k and they all were fine.  Like stated above. If it is running fine and the fluid is not in bad shape then the transmission is as well.

 

I had our 2016 Suburban changed out completely shortly after we purchased it with AMSOIL's ATL.  I did a pan drop at 50k and added a drain plug to the pan that I got from Summit Racing.  So now I can just drain and fill when ever I want with no mess of sucking out the dipstick.

 

If you are interested in AMSOIL ATF PM me your address and I can send a quote delivered to your door.