Duramax ATF service

[stockrex]

My dmax sat a lot, I am at 25k miles and the shifting is not what it used to be.

Time for dmax atf service.
To my surprise GM loaded it up wth Dex VI,

So I have 12.x qts of 13 year old Dex VI.

I did a drain and I was able to drain 6.2 qts.

Here is the plan:
1. 1st drain and fill with fresh Dex VI = 50% ish new ATF
2. 2nd drain and fill with fresh Dex VI = 75% ish new ATF
3. 3rd drain and fill with fresh Dex VI = 88% ish new ATF

Drive this season for another 5k miles and

1. Drain and fill with Transynd 2x = 75% ish Transynd and 22% fresh ATF and 3% old GM OEM ATF

Total cost = $120 for Transynd
20 qts of Dex VI = $120

Total $240 and a lot of ATF to recycle

The MOST Tedious part is holding up the funnel as I pour the ATF through the dip stick hole, any ideas on improving this?

 

[Donald]

Why not do an exchange via the ATF cooling line? Use much less ATF and get a higher %.

 

[Oro_O]

Why not do an exchange via the ATF cooling line? Use much less ATF and get a higher %.

Agree with that.

But honestly, was the truck used in a way to wear the fluid - lots of heavy towing, mountains, something? Otherwise it's unlikely there's really anything THAT wrong with it after 25k miles. A single drain/fill may be enough. I'd start with that. IME DexVI is not a bad fluid that I would go to that extreme on a lower mile unit.

 

[Kira]

OP said above, "To my surprise GM loaded it up with Dex VI,".

What would you expect them to have used? Am I missing something? ....like Dex VI didn't exist 13 years ago?

You're saying the 12.x qt. of Dex VI was factory transmission fill in a 13 year old vehicle of yours? How do you know it's Dex VI?

 

[stockrex]

I am not comfy taking off lines, I have the worst luck with this stuff.

Sorry, I assumed GM filled it with Transynd, it pays to read I guess. Nothing wrong with Dex VI.

Transynd is $40 a gallon
so if I do 3x service with Straight transynd I get

1.5 * 3 * 40 = $180 for 88% transynd and 12% old atf

cheaper and less wastage????

 

[Donald]

I would do nothing until 60K to 75K miles. Install a Magnefine inline filter.

 

[BlakeB]

I would do nothing until 60K to 75K miles. Install a Magnefine inline filter.

These units have a spin-on filter with a magnet.

Amazon.com

 

[BlakeB]

I am not comfy taking off lines, I have the worst luck with this stuff.

Sorry, I assumed GM filled it with Transynd, it pays to read I guess. Nothing wrong with Dex VI.

Transynd is $40 a gallon
so if I do 3x service with Straight transynd I get

1.5 * 3 * 40 = $180 for 88% transynd and 12% old atf

cheaper and less wastage????

Summit has 4 gallons of TES-295 for $127.99, with free shipping over $99. That’s about as cheap as you can find licensed Transynd (TES-295).

Mobil 1 122062 Mobil Delvac 1 ATF | Summit Racing

Free Shipping - Mobil Delvac 1 ATF with qualifying orders of $99. Shop Transmission Fluid at Summit Racing.

www.summitracing.com

 

[nascarnation]

GM wanted to use Dex VI instead of Transynd in the pickups because Dex was pretty much the universal fluid in their factory system, and it was cheaper. For 99% of pickups it's just fine.

 

[stockrex]

Blake, thanks, that is great price.
I went ahead and drained and filled with Dex VI, I had some Mag1 on hand.

I took it out for a spin, shifting was better.

Today I will drain again and fill with Castrol Transmax Dex VI (which I picked up from AAP for $1/qt).

Here is a pic of the first drain, I was able to drain 6.2 qts ish only.

the fluid was kinda pale on the paper towel

 

[stockrex]

Did another drain and fill, same amount drained out this time too.

I could not find a Allison filter cup wrench, it has 12 flutes and it is about 72.xx mm, time to muscle the filter off.

 

[stockrex]

The allison filter was stuck,
I had to get a cup wrench for the filter,
That was an eye opener,
the Transmission filter is a 12 point funky sized filter, I found one on amazon for $13
I will post a pic and details later today.

I did 2 drain and fill with Castrol transmax dex vi, the shifting has improved a bit.

Next will be a drain and fill with Transynd, that will bring the system to

88% new fluids and 50% Transynd

 

[nascarnation]

the Transmission filter is a 12 point funky sized filter, I found one on amazon for $13

We borrowed the filter from the original Saturn automatic. Except in the Saturn it's full flow and on the Allison it only sees oil to the control circuit (valve body). The metal housing is about 2x wall thickness of a typical engine spin-on for cold start burst strength.

 

[stockrex]

We borrowed the filter from the original Saturn automatic. Except in the Saturn it's full flow and on the Allison it only sees oil to the control circuit (valve body). The metal housing is about 2x wall thickness of a typical engine spin-on for cold start burst strength.

I did not know that the saturn filter fit,

Here is the filter wrench for Allision Transmission Filter, it is NOT a regular cup wrench any measure

 

[userfriendly]

I park my truck facing up hill, then let it drip for a few hours. Using this method, it takes 9 US quarts. (8.5L).
A case of 12 covers the transmission, transfer case and power steering.

 

[Ram02]

Once you finish those drain and fills I wouldn’t do it again for 30k-50k Dex VI is pretty good fluid

 

[BlakeB]

 

[weebl]

To the OP, are you saying you did multiple drain/fills with Dex VI first, then again with TES-295?

I gained a lot of info from the mega-thread a few years ago (and the version that also appeared in the Duramax forum) from the Allison fluid engineer, and ended up doing drain and fills on mine, to the level he considered functionally to be the same as 100% TES-295. Based on his recommendations, I figured it would be a long time based on mileage, and I was planning on what would be conservative against his recommendations of about 200,000 km (125,000 miles) interval, so long as my regular checks don't show signs of problems. But I see they also have a time interval attached? I suspect within reason that the time can be ignored (2 years seems short).

Very involved reading the mega threads to anyone inclined (I recommend it if you have an Allison transmission), and it actually got contentious on the Duramax forum with the engineer finally leaving due to personal attacks.

 

[nutdriver]

I park my truck facing up hill, then let it drip for a few hours. Using this method, it takes 9 US quarts. (8.5L).
A case of 12 covers the transmission, transfer case and power steering.

This is helpful as to volume you were able to drain. Did you drop the pan or just the drain plug?

 

[userfriendly]

This is helpful as to volume you were able to drain. Did you drop the pan or just the drain plug?

I Just let it drip until the last drop drips. Sometimes I will change the fluid early if I need the used atf for a lesser vehicle, like a ford escape.
Why all transmission oil pans don't have drain plugs is one of the great mysteries of our time.