I just changed out the spin on filter and fluid at 5,000 miles. I did a double fill with a TES 295 Allison approved fluid instead of the GM Dexron VI. I read various forum reports that said shifting would be smoother, but frankly I wasn't expecting the difference it made.

I used Mobil Delvac because I could get a better price on it shipped, but Castrol's TranSynd or Shell Spirax S6 are also approved. I would go with an approved, not a "meets spec" fluid.

https://www.allisontransmission.com/parts-service/approved-fluids/on-highway-fluids

Guy on a lube forum explained it well. GM outsources transmission to Allison. GM wants to standardize all auto transmissions to use DEX VI. Allison says, that's fine, but we like this better. And it is.

Not going to hunt down where it's posted, but GM's fluids are made by ExxonMobil.....

Will have to dig up the thread, but I found a Duramax forum where a contributor was a former engineer at Allison. Basically, he recommended drain and refill with Transend, run it a while, Drain and refil again, then forget it for 100,000 miles.

Found it:

https://www.duramaxforum.com/forum/transmission-shop/95342-former-allison-transmission-fluids-engineer-mr-transynd.html

Quote:

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Hello to all on this forum. My name is Tom Johnson and I was the Transmission Fluids Engineer at Allison Transmission from 1990 until my retirement in 2009.

Since my retirement from Allison, I'm free to engage in these forums and set some things straight and answer any questions you might have concerning TranSynd or the Alllison fluid specifications (TES-295 and TES-389). I'm also on other industry forums as well and have been getting some really good questions. Incidentally, I wrote most of the current Allison specifications and approved nearly all the oil and fluid products for Allison's On-Highway transmissions (1000/2000 and 3000/4000 Series) and also for the Off-Highway transmissions (5000 thru 9000 Series).

I served on the Lubricant Review Institute's Engine Oil Review Committee for US Army specification oils. I was also a member of the GM Automatic Transmission Fluid Committee for many years where I helped review test data and approve DEXRON-III and DEXRON-VI formulations for GM cars and trucks.

Hope I can help.

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CanyonAg77 said:

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Found it:

https://www.duramaxforum.com/forum/transmission-shop/95342-former-allison-transmission-fluids-engineer-mr-transynd.html

Quote:

---

Hello to all on this forum. My name is Tom Johnson and I was the Transmission Fluids Engineer at Allison Transmission from 1990 until my retirement in 2009.

Since my retirement from Allison, I'm free to engage in these forums and set some things straight and answer any questions you might have concerning TranSynd or the Alllison fluid specifications (TES-295 and TES-389). I'm also on other industry forums as well and have been getting some really good questions. Incidentally, I wrote most of the current Allison specifications and approved nearly all the oil and fluid products for Allison's On-Highway transmissions (1000/2000 and 3000/4000 Series) and also for the Off-Highway transmissions (5000 thru 9000 Series).

I served on the Lubricant Review Institute's Engine Oil Review Committee for US Army specification oils. I was also a member of the GM Automatic Transmission Fluid Committee for many years where I helped review test data and approve DEXRON-III and DEXRON-VI formulations for GM cars and trucks.

Hope I can help.

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Meh

I probably know more about transmissions and fluid than that guy.... (most dirty leg rednecks)

Dr. Doctor said:

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CanyonAg77 said:

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Found it:

https://www.duramaxforum.com/forum/transmission-shop/95342-former-allison-transmission-fluids-engineer-mr-transynd.html

Quote:

---

Hello to all on this forum. My name is Tom Johnson and I was the Transmission Fluids Engineer at Allison Transmission from 1990 until my retirement in 2009.

Since my retirement from Allison, I'm free to engage in these forums and set some things straight and answer any questions you might have concerning TranSynd or the Alllison fluid specifications (TES-295 and TES-389). I'm also on other industry forums as well and have been getting some really good questions. Incidentally, I wrote most of the current Allison specifications and approved nearly all the oil and fluid products for Allison's On-Highway transmissions (1000/2000 and 3000/4000 Series) and also for the Off-Highway transmissions (5000 thru 9000 Series).

I served on the Lubricant Review Institute's Engine Oil Review Committee for US Army specification oils. I was also a member of the GM Automatic Transmission Fluid Committee for many years where I helped review test data and approve DEXRON-III and DEXRON-VI formulations for GM cars and trucks.

Hope I can help.

---

---

Meh

I probably know more about transmissions and fluid than that guy.... (most dirty leg rednecks)

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Are you an oilfield welder?

WP69 said:

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Guy on a lube forum

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Username checks out.