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Discussion Starter · #1 ·
So i have not had the trans fluid and filter chang's on my truck and i was thinking about doing it. So i have called around to a few shops and got a quote to have it done but one shop i called the guy told me you are not really supported to change the fluid unless you have too. Is this true or is this guy just retarded? Because no other shop told be this and another shop told me i should go ahead and change the internal filter also while I'm at it. Truck has 160k on it. Not many for a duramax and an allison but i still think it should be changed. At least the fluid and the spin on filter.

Lmm Guy
 

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They don't know Allisons. They're going on experience with cheap car trannys, which you don't have.
DON'T let 'em hook up a machine to it.

Pull the drain plug, then drop the pan, clean & inspect. Pan back, refill with Mob Delvac...2 gallons needed.
The pan gasket is a lifetime reusable.

If you also pull and swap the inner sump filter & the spin-on, you'll need another 2 qts,...or another gallon, as they only sell Delvac in Gals or 5-Gals.

In 50k miles, repeat.
 

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Discussion Starter · #5 ·
They don't know Allisons. They're going on experience with cheap car trannys, which you don't have.
DON'T let 'em hook up a machine to it.

Pull the drain plug, then drop the pan, clean & inspect. Pan back, refill with Mob Delvac...2 gallons needed.
The pan gasket is a lifetime reusable.

If you also pull and swap the inner sump filter & the spin-on, you'll need another 2 qts,...or another gallon, as they only sell Delvac in Gals or 5-Gals.

In 50k miles, repeat.
Is that fluid red also?

Lmm Guy
 

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It's all red. Mobile Delvac or Castrol Transynd, Allison recommended TES-295 fluid.
Delvac is cheaper...See summit link above.
3-gals of Delvac and both filters, $130.
It's not a high skill level to do it.....driveway, sockets, and drain pan.
 

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Discussion Starter · #7 ·
It's all red. Mobile Delvac or Castrol Transynd, Allison recommended TES-295 fluid.

3-gals of Delvac and both filters, $130.
It's not a high skill level to do it.....driveway, sockets, and drain pan.
You said it like oil. But when i pull the trand stick to check it it looks redish is that the right color?

Lmm Guy
 

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Your stock fluid is red Dex-VI.
Pretty much all Trans fluid is REd.
 

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Do you have links to the fluid i need
See post #4.

Filters, go to the Allison website and find the nearest parts dealer in your area.
They're everywhere Trucks are. You'll get the best filters for the cheapest price.
They'll most likely have to order your inner filter, as it's for the shallow pan and everything they work on (big trucks) use the deep pan filter.
 

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Discussion Starter · #11 ·
See post #4.

Filters, go to the Allison website and find the nearest parts dealer in your area.
They're everywhere Trucks are. You'll get the best filters for the cheapest price.
They'll most likely have to order your inner filter, as it's for the shallow pan and everything they work on (big trucks) use the deep pan filter.
Thanks and one more question. If i decide to just change the fluid and the spin on filter is it safe for the fluid left that dont drain out to mix with a different type of fluid?

Lmm Guy
 

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Yep.
You're only draining/changing 2-ish gallons.
The whole system is 5-ish gallons.
 

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Thanks and one more question. If i decide to just change the fluid and the spin on filter is it safe for the fluid left that dont drain out to mix with a different type of fluid?

Lmm Guy
I would definitely drop the pan. Easy 30 minute job plus if you remove and inspect the internal filter you have drained an additional 2 qts of fluid.

If you find some hard parts in the pan you will know there is probably something wrong with the transmission.

If you find nothing in the pan then you have some confidence that the transmission is in good condition.
 

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I would definitely drop the pan. Easy 30 minute job plus if you remove and inspect the internal filter you have drained an additional 2 qts of fluid.



If you find some hard parts in the pan you will know there is probably something wrong with the transmission.



If you find nothing in the pan then you have some confidence that the transmission is in good condition.


I highly recommend changing the inner filter while you鈥檙e at it, especially at 160,000 miles. They鈥檙e supposed to be good for a lot of miles and some recommend not touching them. Over time, the o-ring on the inner filter, will harden and can start causing problems, by sucking air around the filter. It鈥檒l cause foaming and can cause shift problems. I found that on my 2007.5. Doesn鈥檛 cost much and is good insurance to go ahead and change it.


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Having worked on auto trans for an OEM IMHO do not drop the pan as often this will cause leaks around the gasket. I believe GM says 50k for fluid changes. The best way is to do a complete flush as about half the fluid is in the converter. Allison uses larger diameter lines and most shops don't have the fittings so u have to go to the dealer. Arguably the auto trans is far complicated than an engine. Would u wait 160000 miles for an oil change?
 

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When changing your spin on external filter don't forget to make sure to put the magnet on the new filter - it might come off with the filter.
 

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For what it's worth, my GMC dealer recommends flushing the Allison every 60,000 miles when used in a non towing, highway application and every 25 - 30,000 when towing or working it hard.
 
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