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Discussion Starter · #1 ·
So I've been reading on here for a while now about switching to transynd, but my question is should I do take the risk in switching out the fluid since I have 360k on my truck.

I personally don't think it's going to do anything bad, but I've got a few naysayers telling me just to stick with what's in it.



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You've put all of those miles on?

Drain and drop the pan, just under 2 gallons.
There's 5+ gallons in the system. You're not going to hurt anything with a small %.
I think I'd also change the inner filter too (along with the spin-on) and inspect the pan for any debris.
Have 10 qts on-hand with that.

Most car autos with high mileage and never having been serviced, that's the theory (leave it alone), as a full fresh batch of fluid can have old worn parts suddenly biting like new parts....and shortly there after, you have a trans problem you didn't have before.
 

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Discussion Starter · #3 ·
I bought the truck with a little over 340k on it and they told me it was serviced when it needed to be. I'm assuming all they did was the spin on so I'm wanting to change the interal also.

When I change it should I just drop the pan and go that route or would it be worth the time and money to do the double drain?

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I did mine right at 350K. Now at 405k. Only thing that happened is it now shifts a lot smoother. I used the Mobil 1 version.

I did it a little different than the standard procedure.

Dropped the pan & changed both filters. Refilled with TES-295. Drove it for about a month. Dropped the pan & changed both filters. Refilled with TES-295.
 

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I'm assuming all they did was the spin on....
Maybe, or not. At least something was done.

When I change it should I just drop the pan and go that route or would it be worth the time and money to do the double drain?
IMO, you don't really gain. Double drain (TES-295), you're good for 100k miles.
Drain/drop the pan, replace both filters, that's 10qts.
50k miles later (or less, your choice), drain/drop the pan, about 7.5-8qts.

Same mileage in the end. Source that spin-on from Allison (under $10) and change it along the way when you do your fuel filter, and I think you're GTG.

Consider Delvac full syn too, many times le$$ $$ than the Castrol.
 

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Summit Racing has the best price on the Mobil 1 stuff I've seen.
 
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Consider Delvac full syn too, many times le$$ $$ than the Castrol.
And the Mobile Delvac is more color stable too. I changed mine to Transynd 30,000 ago and it is now orange and much harder to read on the dipstick. The Delvac stays red.

When I replace it I will use the Delvac.
 

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Just looked it up in my log - changed to TES-295 at 362,000 miles, not 350k.
 

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go on the allison web site and do what they tell you, I have posted this before and just maybe allison knows what they are talking about, no need to drop pan unless overhaul. Hook would be right as you don't know the truck so maybe drop the pan and do a allison deep pan, cheap insurance.
I have run Transynd for a million + miles in 4 trucks , had fair share of failures but never a trans failure FWIW
 

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Discussion Starter · #10 ·
go on the allison web site and do what they tell you, I have posted this before and just maybe allison knows what they are talking about, no need to drop pan unless overhaul. Hook would be right as you don't know the truck so maybe drop the pan and do a allison deep pan, cheap insurance.

I have run Transynd for a million + miles in 4 trucks , had fair share of failures but never a trans failure FWIW
https://www.summitracing.com/parts/...rgE76N41hrJwP0l7GK7VHKus9GqV_d7gaAvbwEALw_wcB

Found this after going there. Is it the right one or is there a different one.

How beneficial would doing a deep pan swap be?

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I ran the deep pan cause allison uses it for severe service , It won't really reduce temps just takes longer to get there and cools a little quicker , I don't claim to understand but the harder a piece of equipment works the more oil the mfg. usually has in the system. I notice alot of MFG will extend the warranty with synthetic oil , I like transynd cause Allison recommends it, but it is getting awfully pricey las few years. Madjack Diesel had a good deal on deep pan and oil /filters , Duramax store does as well I believe.
https://www.madjackdiesel.com/Allison-Deep-Trans-Pan-Kit-With-Fluid-p/mjd-tpfkit.htm
https://dmaxstore.com/products/?route=product/product&path=12_88&product_id=144
 

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Discussion Starter · #14 ·
So, it's been 3 months since I started thinking about doing this "upgrade" and I'm finally doing it tonight. My new question is, should I take the cooler lines loose and drain them too or just drop the pan? The pan is currently off and I'm letting as much drip as possible but I didn't know if it would hurt or benefit taking the lines off.

Also, both magnets, filter and pan, were covered in a nice black sludge, but the fluid didn't smell burnt or have any darkness to it. Is this something to be concerned with or normal wear?

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I didn't drop the pan when I changed. I can't see taking the cooler lines loose would have any real benefit. Too much fluid carried in the torque converter, even with a double fill method.
 

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normal to find paste.
Pan off, drop the internal filter, more fluid gushes out...then replace.

Or not. Just go with what fills the pan.
 

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I didn't know if it would hurt or benefit taking the lines off.
The OEM trans lines are notorious for leaking. I would not touch them if possible. I take my LBZ to the local Freightliner / Allison heavy truck dealer for trans service. They remove the trans line and draw the new Transynd / Mobil 1. In through the open line and push the old stuff out. Basically a fluid exchange. My trans line started leaking after this procedure. They warned me up front that may occur and I said go ahead so that鈥檚 on me. I went with aftermarket lines after that.

I asked for Transynd which they supplied for an additional cost.They typically use Mobil Delvac TES 295 certified fluid. They said they have very good luck with it and it costs less.
 

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I have always done the flush (HOOT) and had the return line off the trans 4 or 5 times with no leak issues. The trick is to keep everything clean and be certain that the line is seated properly when reinstalling.. Having run a shop, the techs don't always keep everything clean, they get in a hurry, time is money, not their truck.This isn't true for all techs but it happens.
Always used transynd and last time switched to the Delvac with better results. Shifts are more uniform and color retention with the Delvac is much better than Transynd hands down and Delvac is $10 per gallon less, that is significant when doing a flush.
 

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Discussion Starter · #19 ·
Ok so I got the transmission all buttoned up. Drained over 2.5 gallons so I put 2.5 back in and when I get it off jackstands I'll warm it up and top off if needed.

On to the new project, front axle seals.

Thanks for all the help on this. Stay tuned for questions/problems with the front axle.

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