Thoughts on a transmission drop and refill

[Denali GMC 87]

Hello guys. I know I'm probably going to get possibly mixed responses. But I'm going to ask anyway. My 2008 Denali xl awd has 231k miles, bought at 219k miles. Seems to shift great and no issues. I put roughly 5k and year on it and have owned it 4 years. I have changed all the other driveline fluids except the transmission. Would it be a bad idea to perform just a drop and refill with a fresh transmission filter especially with the mileage. I take good care of my vehicles and even this one, even though it has high mileage runs fantastic. Input would be appreciated.

 

[SpareParts]

Just do it!

 

[Marky Dissod]

... changed all the other driveline fluids except the transmission.
Would it be a bad idea to perform just a drop and refill with a fresh transmission filter, especially with the mileage?

Just do it!

It would be a GOOD idea, do it. You don't get to say

... I take good care of my vehicles ...

until you change the ATF.

 

[Bigburb3500]

Agreed. It’s ultimately not difficult or even that time consuming. Just be sure to get the level correct afterwards.

 

[donjetman]

Hello guys. I know I'm probably going to get possibly mixed responses. But I'm going to ask anyway. My 2008 Denali xl awd has 231k miles, bought at 219k miles. Seems to shift great and no issues. I put roughly 5k and year on it and have owned it 4 years. I have changed all the other driveline fluids except the transmission. Would it be a bad idea to perform just a drop and refill with a fresh transmission filter especially with the mileage. I take good care of my vehicles and even this one, even though it has high mileage runs fantastic. Input would be appreciated.

Its a good idea

 

[Denali GMC 87]

Why I am asking is due to hearing and reading various opinions because of the high mileage. Even when I first bought it I was skeptical because you hear mixed opinions on this topic. But I posted on here due to the history of this model transmission.

 

[Bigburb3500]

Why I am asking is due to hearing and reading various opinions because of the high mileage. Even when I first bought it I was skeptical because you hear mixed opinions on this topic. But I posted on here due to the history of this model transmission.

If the fluid has never been changed then you might want to run it for a bit then do another pan drop filter in 5-10k miles. Part of the issues are there is build up and the new fluids with fresh detergents breaks up buildup that has accumulated.

Or at least that’s the theory.

 

[SpareParts]

A flush might give you problems, who knows for sure?
Changing the fluid and filter will only help.

 

[Marky Dissod]

If the fluid has never been changed then you might want to run it for a bit then do another pan drop filter in 5-10k miles.
Part of the issues are there is build up and the new fluids with fresh detergents breaks up buildup that has accumulated.
Or at least that’s the theory.

That theory applies to Dex3, but not to Dex6. Don't flush, just drop the pan and drain that much of the fluid.

 

[intheburbs]

Personally, I'm a fan of full fluid replacement. I've done it on every vehicle I've bought used (4 of the 5 in my Sig), and I do it as part of routine maintenance, every 50k (or less, depending on duty cycle).

The Denali (bought used in 2015 at 70k miles) now has 160k miles.

The Suburban (bought used in 2013 at 100k miles) now has 268k miles.

The 2001 Suburban was bought in 2005 with 75k miles, now has 320k miles.

All transmissions still function perfectly. And we don't drive like grandma.

 

[SpareParts]

This is the way i more or less do it. I usually run about 3 gallons through it.

 

[Doubeleive]

Hello guys. I know I'm probably going to get possibly mixed responses. But I'm going to ask anyway. My 2008 Denali xl awd has 231k miles, bought at 219k miles. Seems to shift great and no issues. I put roughly 5k and year on it and have owned it 4 years. I have changed all the other driveline fluids except the transmission. Would it be a bad idea to perform just a drop and refill with a fresh transmission filter especially with the mileage. I take good care of my vehicles and even this one, even though it has high mileage runs fantastic. Input would be appreciated.

get a clean white paper towel, pull the transmission dipstick out and wipe some of the fluid on the white towel and post a picture of it on here.
Doing that will provide a little more insight into the condition of your transmission.
for reference this is fresh fluid from a healthy transmission

 

[Doubeleive]

crickets...

 

[Denali GMC 87]

See photo.

 

[SpareParts]

Dang. Well pas time to change!.

 

[donjetman]

Hello guys. I know I'm probably going to get possibly mixed responses. But I'm going to ask anyway. My 2008 Denali xl awd has 231k miles, bought at 219k miles. Seems to shift great and no issues. I put roughly 5k and year on it and have owned it 4 years. I have changed all the other driveline fluids except the transmission. Would it be a bad idea to perform just a drop and refill with a fresh transmission filter especially with the mileage. I take good care of my vehicles and even this one, even though it has high mileage runs fantastic. Input would be appreciated.

To Change or Not Change my Transmission Fluid & Filter

Hello Forum Members, I am the original owner of a somewhat well maintained 2011 Tahoe. I say somewhat because it have 129K miles and I've kept all the maintenance up on it with exception to the changing the tranny fluid. And the only reason why I haven't done so, it appears GM doesn't make it...

www.tahoeyukonforum.com

 

[Fless]

Time to get after it. Drop the pan and replace the filter, replenish the fluid level with new. Then plan to drain the pan again (like @Bigburb3500 mentioned) in 5k to 10k miles. Think about replacing the pan with one that has a drain plug, if they're available. Makes it easier to drain and fill.

The method @SpareParts would use the internal pump to exchange all the fluid in one shot. But note that when you go to push a fitting into the radiator port, I think you can install the clip first, then push the line into the fitting. Save some grief about putting that clip on with the line in the way.

 

[rdezs]

I converted over to AN6 lines..... Real quick to disconnect the return, hook up a long hose into a bucket. I let it pump about 8 quarts out, then put a quarts back in, and repeat and I start to see the new fluid.

 

[justirv]

Now is a good time to install a 40k cooler, and plumb with AN6 as @rdezs mentioned. A new pan with drain plug will encourage you to do timely fluid changes.

 

[Doubeleive]

See photo.View attachment 477923

well it probably hasn't been changed in a good long while......
still find it hard to believe that gm puts a 100k interval in the owners manual, complete b.s.
I prefer to do mine about every 25-30k, but I drive it like I stole it to.