Chevy and GMC Duramax Diesel Forum banner
  • Hey Everyone! Enter your ride HERE to be a part of this months Ride of the Month Challenge!
1 - 5 of 5 Posts

·
Registered
2004.5 Chevy Silverado 2500hd 6.6L LLY/Allison, 4x4. LS, ext cab, long box.
Joined
·
6 Posts
Discussion Starter · #1 ·
Real quick

04,5 lly. 300k on allison trans and engine
And i bought the internal and external filters for the allison and pan gasket.

Should i (with having no experience at all with teansmissions. )
Attempt to change both filters and then i assume id need to refil trans.
With.
What might be preferred with 300k on the fluid and filters never changed or anything

Valvoline dex 3.
Regular?
Synth blend
Full Sythn ?

Someone mebtioned i find a place to have the trans hot flushed.

I read somethin about castrol .. Synth.
Bouhht allison and acdrlco filters and trans pan gasket

If its safe to do at home. Would i esssential just go about it like a oil change.
Drain old. Fill new. Install clean filters and jist call it good

Thanks .
 

·
Registered
Joined
·
312 Posts
I haven't changed my internal filter, but I only have 159k miles, plus the official Allison advice is to change it only if you have the pan off for some other reason. Still, a lot others have done it. Some had problems with the internal filter falling off, but that might only be if you switch to a deep pan (which isn't usually necessary). Someone who has changed with a regular pan can chime in on changing the internal.

The preferred external filter is genuine Allison.

The preferred ATF has been a TES-295 approved fluid, such as Castrol Transynd or Mobil Delvac, which are not usually available at regular auto parts stores. Online or truck centers. There's a new TES-668 ATF out but I haven't tried it yet.

For me, next best choice is Mobil 1 Fully Synthetic Dex/Merc ATF which says "for 2005 and older GM". I haven't used this in quite a few years, but I assume it's still around (I use Mobil Delvac TES-295).

For the old Allisons that came with Dex-III, it's important NOT to use Dex-VI because of some seal incompatibility. Dex-III is officially retired, so it may or may not be on labels.

NEVER power flush an Allison. It may cause the clutch materials to come unglued (or something like that). The safest method is a simple drain'n'fill with a new external filter. If you feel the need, drive a few hundred miles and repeat the drain'n'fill. Each fill usually takes about 7.4 quarts.

You might measure how much comes out to know how much to put back in. Also, the correct level is about 1/4th of the way up into the hot hash area on the dip stick at 170*F; The dash gauge for the transmission tends to be quite accurate, whereas the dash gauge for the engine temp is a big fat lie (but that's another story).
 

·
Registered
2004.5 Chevy Silverado 2500hd 6.6L LLY/Allison, 4x4. LS, ext cab, long box.
Joined
·
6 Posts
Discussion Starter · #3 ·
Thanks,

Dex lll is depricated.. Well Makes sense as to why i thought it seemed a bit more tasking. Than it should of. To find it Lol

I ended up purchasing 8 quarts of valvoline.
Dex/merc atf in a blue colored container
It says for gm made before 06.
And lists
GM DEXRON-lll
Allison c-4 & TES-389
On the back label.

I bought the allison red spin on. And just in case a new magnet

Power flush and hot flush. One and same.

And so what i think im understanding is that an automatic trans is treated or thought about the same no matter gas or diesel wether its nevet been. Or its been multiples of 10's of thousands of miles between fluid changes.
And it aint broke. Dont touch it dont open it etc. Lol.

I did get a bit more detail as to the posdibility of the trans fluid being changed out, my step dad. I guess would always take it in for routine oil changes. And was the type that would always take the service persons advice if the the service place recommended "x"service be performed.etc. so. That was somewhat of a relief. So i prolly wont need ALL 8 quarts. Lol. (Itd be a welcome surpise as i can definitely. Utilize the 70 bucks or so. Guessing return of 6 of the 8. Quarts. Lol.)

So am i correct in understandimg that its safe nowadays. With both atf and motor oil. To switch to synthetic at any mileage etc.

Transend that was it. And yea delvac mobil stuff. I was seeing both are well liked.

Safe to say i can also return the trans pan gasket and the internal trans filter
As well. ? ]
 

·
Registered
2003 GMC 2500HD 4x4 Banks Super Scoop, Banks Rear Dif Cover, Mechman 320A alternator, S&B fuel tank
Joined
·
131 Posts
The advantage of dropping the pan and swapping the internal filter is you get more fluid out and can get an idea of how things look.
It's a quick easy job.
The Mobil Delvac which meets the T295 standard is available at Advance Autoparts for sure.
 

·
Registered
Joined
·
312 Posts
... So i prolly wont need ALL 8 quarts. ...
Whether you drain'n'fill or drop the pan, you'll need between 7.4 and 8 quarts of new ATF.
 
  • Like
Reactions: jtkc
1 - 5 of 5 Posts
Top