# Allison transmission flush?



## RCsLawncare (Oct 24, 2008)

Dealer says flush it for $250 bucks. It has 140k, got it with 110k with no maintenance history. Kinda wondering if I should leave it or have it flushed. Good? Bad? What do you all thing?


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## sweetk30 (Sep 3, 2006)

easy to do. i just did one.

8 qt of good atf dextron 3 or better.

1 spin on filter for the allision.

around 30 min and basic tools.

pull drain plug on pan. catch the fluid. reinstall plug.

remove spin on filter. AND SWAP the magnet over if stuck to the filter. install the new one. http://www.napaautoparts.com/Search/Detail.aspx?A=ATP18592_0259785570&An=599001+102003+50014+2014039

refill the tranny with around 7-8 qt of fluid till in the cross hatches on the stick.

easy and simple. with that mileage thats all i would do.


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## RCsLawncare (Oct 24, 2008)

So just draining the fluid would be better than actually flushing it. Thats what I wanted to do, but they had to give me the run around on why its better for them to do it.


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## RCsLawncare (Oct 24, 2008)

Also, what's the best fluid I can get if Im just draining it. Can I mix something like royal purple into it? Any better or just stick with the basic stuff?


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## Q101ATFD (Oct 24, 2006)

The best stuff, hands down, for an Allison transmission is Transynd, made by Allison. They claim a 100,000 mile drain interval when you have 90+% Transynd. One drain and refill will get you to 57%, and another drain and refill will put you at 83%. Of course you can use any approved Dexron-VI, however, I think that the MY 2003 Allison seals don't like synthetic fluids, with the exception of Transynd.

EDIT: Per Allison, synthetic fluids should only be used in Allison transmissions with a serial number greater than: 6301670488 OR 6320784373. Numbers before those should only use non-synthetic Dexron-III.

Clear as mud?


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## RCsLawncare (Oct 24, 2008)

Good to know, I appreciate the info!!!


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## 2COR517 (Oct 23, 2008)

Here's a good procedure to safely exchange the fluid in your transmission. I don't know what the total fluid capacity of the Allison is, it should be in your owner's manual. You'll want at least a couple extra quarts. This will give you 90% plus new fluid.

http://www.plowsite.com/showthread.php?t=92981


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## stacks04 (Jan 22, 2008)

do the flush. the allison holds about 15-16 qts between the torque converter and the coolers. the trans also has 2 filters, the spin on and an internal filter like always. that kinda milage i would do everything. it will be much cheaper than the 2 grand to rebuild it if it takes a dump. just draining the pan only gets 50% of the fluid. 
if you go to synthetic you will need to change the fluid a few times also if you dont do the system flush. you will need atleast 2 drain and fills with the synthetic to be more than 75% synthetic fluid.


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## brad96z28 (Aug 21, 2005)

Draining it only does about half the fluid. Thats like pissing in the ocean. Might as well do it rite if ur gona do it at all.Im using dex 6 full syn in mine.


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## grandview (Oct 9, 2005)

I thought BB said not to flush it as recommended by GM.


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## 2COR517 (Oct 23, 2008)

grandview;971240 said:


> I thought BB said not to flush it as recommended by GM.


I'm sure he'll chime in soon. He "endorses" the *exchange *procedure I outlined in the thread I linked, at least for the 4L80e and 4L60e transmissions. I'm not sure why the Allison would be different, but he is the expert.

Where's the "we're not worthy" smilie thingie :laughing:


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## sweetk30 (Sep 3, 2006)

make sure thay have a machine for allision trannys. 

a std flush machine cant handle the pressures of a allision tranny. 

i know of a shop that blew one up. :laughing:


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## 2COR517 (Oct 23, 2008)

The Allisons have a higher pressure on the cooler lines?


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## exmark1 (Nov 30, 2005)

With the higher milage I would just drop the pan and filter and fill dont power flush the system out. 

We drop the pan and filter on all of our truck 2 x per year or every 10,000 miles I have never replaced a transmission since we started doing this 5 years ago.
We have some higher milage trucks that have been plowing for years this way with no issues!
2003 Dodge Diesel 101,000 
2001 Dodge Diesel 148,000
2000 Ford F-250 Diesel 125,000

All 3 have the original tranmissions with no work done to them! The 2001 Dodge has been plowing and towing daily since it was new


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## brad96z28 (Aug 21, 2005)

exmark1;971422 said:


> With the higher milage I would just drop the pan and filter and fill dont power flush the system out.
> 
> We drop the pan and filter on all of our truck 2 x per year or every 10,000 miles I have never replaced a transmission since we started doing this 5 years ago.
> We have some higher milage trucks that have been plowing for years this way with no issues!
> ...


 A flush machine does not use any added pressure then what the trans makes on its own. It simply exchanges the fluid. As the old fluid is exiting the line the new fluid goes in the other side. How does that hurt anything? Why not do it please explain? I do them several times a week, and it is recomended by most auto manufacturers.


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## brad96z28 (Aug 21, 2005)

2COR517;971400 said:


> The Allisons have a higher pressure on the cooler lines?


 Yes they do, copmared to most of the trans that I have had gauges on. And they have some huge adaptors to hook up to at the cooler lines.


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## RCsLawncare (Oct 24, 2008)

pictured a flush putting new fluid in at a high pressure forcing it through the transmission. Id rather know it out in one shot. After doing that, i will drain and change the filter every 15k. doe's that sound like a good plan? Just don't want to hurt it as it costs a lot and runs fine now!


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## brad96z28 (Aug 21, 2005)

RCsLawncare;971572 said:


> pictured a flush putting new fluid in at a high pressure forcing it through the transmission. Id rather know it out in one shot. After doing that, i will drain and change the filter every 15k. doe's that sound like a good plan? Just don't want to hurt it as it costs a lot and runs fine now!


Sounds like the procedure above does almost the same as my flush machine just not as neat. I would try that If I where u. And with flush machines they should call it a fluid exchange not a flush. Where someone came up with power flush thats a new one to me. Ur not gona hurt anything whatever u decide to do. But the more fluid u exchange the better. 15k is a bit early 30 k is more like it unless it starts to look dirty before then.But that will also depend on what fluid u end up using.


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## NICHOLS LANDSCA (Sep 15, 2007)

Q101ATFD;970208 said:


> The best stuff, hands down, for an Allison transmission is Transynd, made by Allison. They claim a 100,000 mile drain interval when you have 90+% Transynd. One drain and refill will get you to 57%, and another drain and refill will put you at 83%. Of course you can use any approved Dexron-VI, however, I think that the MY 2003 Allison seals don't like synthetic fluids, with the exception of Transynd.
> 
> EDIT: Per Allison, synthetic fluids should only be used in Allison transmissions with a serial number greater than: 6301670488 OR 6320784373. Numbers before those should only use non-synthetic Dexron-III.
> 
> Clear as mud?


The serial # issue is dependent on which plant it was made in. I don't remember which is which.


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## B&B (Nov 4, 2006)

brad96z28;971497 said:


> I do them several times a week, and it is recomended by most auto manufacturers.


Show me proof where "most" OEM auto manufactures endorse a trans fluid exchange procedure be done as a periodic preventative maintenance procedure.

Dealers and shops do, and so do the manufactures that produce the exchange machines, but you won't find enough OEM auto manufactures to group into your "most" category. Because they do not recommend or endorse trans fluid exchanges as a periodic preventative maintenance item.


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## RCsLawncare (Oct 24, 2008)

B&B;971684 said:


> Show me proof where "most" OEM auto manufactures endorse a trans fluid exchange procedure be done as a periodic preventative maintenance procedure.
> 
> Dealers and shops do, and so do the manufactures that produce the exchange machines, but you won't find enough OEM auto manufactures to group into your "most" category. Because they do not recommend or endorse trans fluid exchanges as a periodic preventative maintenance item.


YOu seem to be the man to talk to on here about this. What's the verdict? Let the dealer "exchange" the fluid or just drain it and put a new external filter on it and call it done, and go that route? If they won't hurt it, GM dealer of course, they can do it.


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## B&B (Nov 4, 2006)

Ok let me break it down a little along with explaining my post in regards to OEM manufactures endorsing a periodic fluid exchange. It was simply to debunk a popular consumer misconception that they as a whole do recommend them, which they do not. It's urban legend created for nothing but the conception of producing extra shop revenue at the thought of the consumers that it needs to be done as per OEM recommendations to prolong the life of the trans, or to satisfy any possible remaining OEM warranty's and is un factual. And in this example since were in the GM section the ONLY time GM endorses a flush of any kind is on the trans cooler ONLY and only by itself when a restricted cooler is suspected. They do not endorse a flushing of any type through the actual transmission. So is it a good or bad idea to do it? That depends on who's doing the job, if they're also changing filters, and what type of machine they're using. And that requires a little more detail in its explanation....

A "flush" and an exchange are two words that are used together but are two different things, and that is where the confusions lie. A flush is when you have a machine that back flushes and/or agitates through the system in a effort to remove/loosen debris. But thankfully those machines are a dying breed these days because they created far more harm than good on a neglected trans. With an exchange you're only replacing the old fluid with new in the same direction as normal flow. NEVER flush a trans, but exchanges are a great way to remove virtually all traces of the old fluid (whether it's done by a machine or by the DIY method as 2COR provided the link to). However to do so properly you also have to change the filter....which many do not. They simply swap the fluid and call it a day. However there's a slight flaw in the slaw when it pertains specifically to an Allison and it's internal filter. Because Allison doesn't recommend it be changed during routine service as it's intended to last the life of the trans and should last to the first overhaul; although many guys that work these trucks hard still take the preventative route and change it about every 50K or so and is also what I do and recommend along with also changing the external filter about every 20K or so, or once a year regardless of mileage. It's a cheap insurance plan to follow.

The cooler line exchange method (either by machine or using 2COR's DIY linked method) works great on any trans and is far better at removing more of the old fluid than simply draining the pan alone. Especially with the Allison as the drain plug is recessed deep into the pan, thus still leaves over 2 full qts of old fluid remaining in the pan, let alone in the rest of the system.

Bottom line to all this RC is since you have no previous service records on the truck it's time to take care of the trans. This places it on a schedule you will then not only know for sure, but also removes any doubts as to when (or if) it has ever been done previously. Is it worth $250? That depends on whether that also includes changing the filters and what fluid they're exchanging with. Fluid choice is up to you but if you have the aptitude to do the job yourself you could switch to full synthetic and change both the filters for much less than that dealer quote while ending up with a better fluid protecting the trans in the process. But if you're not comfortable tacking the job yourself then by all means pay the money to have it done but ask the right questions to see exactly what you're getting for that money. But either route you decide to go.....do it.





A few other details and questions that have popped up in this thread while we're on the subject....

OEM fill Dex VI is not full synthetic, it is a semi-synthetic. However there are oil manufactures that produce full synthetic Dex VI as an OEM approved replacement so depending on what you're buying brand wise during a replacement can be semi or full synthetic.

For Allison's specifically, you can run any TES-295 Allison spec'd fluid as well in any model year. Allison's own TranSynd (which is produced by Castrol), Mobil 1's full synthetic ATF (Delvac) or Amsoil's Torqdrive are all good choices when going full synthetic. If you're sticking with regular old dino fluid on one that was originally spec'd with it then Dex3 is the preferred fluid of choice. For capacities, a drain only will require 5 qts, a pan drop with an external filter change will require 8 qts, and a total exchange will use up to 5 gallon.

A question was also asked about cooler line pressures on an Allison in comparison to other transmissions. And to detail, pre mid-'04 model year Allison's without the modulated main line valve can and will run full line pressure through the cooler at times so it's possible to have 200 PSI in the cooler system so if you disconnect the cooler lines for any reason be damn sure you get the retainer clip properly and fully re-installed because it will easily blow the line off at the most inopportune time, thus making not only a major mess but also present a fire hazard. They also run at a higher GPM through the cooler circuit than most transmissions (and hence the need for the large 5/8" cooler lines) so if you use the homebrew cooler exchange method have a helper on hand or else you need to be quick on your toes to prevent running it dry. An Allison is a very redundant transmission but like any other trans one thing it can't tolerate for long is to be run low of fluid.


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## 2COR517 (Oct 23, 2008)

So with cooler line pressures approaching 200 PSI, do they use the typical radiator tank cooler? And do aftermarket external coolers have to be specific for the Allison trans, or can most of them handle the 200 PSI?


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## RCsLawncare (Oct 24, 2008)

B&B;971744 said:


> Ok let me break it down a little along with explaining my post in regards to OEM manufactures endorsing a periodic fluid exchange. It was simply to debunk a popular consumer misconception that they as a whole do recommend them, which they do not. It's urban legend created for nothing but the conception of producing extra shop revenue at the thought of the consumers that it needs to be done as per OEM recommendations to prolong the life of the trans, or to satisfy any possible remaining OEM warranty's and is un factual. And in this example since were in the GM section the ONLY time GM endorses a flush of any kind is on the trans cooler ONLY and only by itself when a restricted cooler is suspected. They do not endorse a flushing of any type through the actual transmission. So is it a good or bad idea to do it? That depends on who's doing the job, if they're also changing filters, and what type of machine they're using. And that requires a little more detail in its explanation....
> 
> A "flush" and an exchange are two words that are used together but are two different things, and that is where the confusions lie. A flush is when you have a machine that back flushes and/or agitates through the system in a effort to remove/loosen debris. But thankfully those machines are a dying breed these days because they created far more harm than good on a neglected trans. With an exchange you're only replacing the old fluid with new in the same direction as normal flow. NEVER flush a trans, but exchanges are a great way to remove virtually all traces of the old fluid (whether it's done by a machine or by the DIY method as 2COR provided the link to). However to do so properly you also have to change the filter....which many do not. They simply swap the fluid and call it a day. However there's a slight flaw in the slaw when it pertains specifically to an Allison and it's internal filter. Because Allison doesn't recommend it be changed during routine service as it's intended to last the life of the trans and should last to the first overhaul; although many guys that work these trucks hard still take the preventative route and change it about every 50K or so and is also what I do and recommend along with also changing the external filter about every 20K or so, or once a year regardless of mileage. It's a cheap insurance plan to follow.
> 
> ...


Wow! Thats is some knowledge right there! But on a more serious note, I will get this done in the next week and let you know what I ended up doing. This post defiantly answered all of my and some I didn't even think about at once! Thank you for your feedback!


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## B&B (Nov 4, 2006)

2COR517;971784 said:


> So with cooler line pressures approaching 200 PSI, do they use the typical radiator tank cooler? And do aftermarket external coolers have to be specific for the Allison trans, or can most of them handle the 200 PSI?


Yes you still have a radiator mounted heat exchanger with an Allison just as with any other trans. However it has a higher flow capacity than what you'd find in your average radiator. Same with any factory or aftermarket external coolers too, most are rated to 200 psi minimum but not all will satisfy the flow requirements for an Allison and that is what is just as important. You need the cooler system as unrestricted as possible and above Allison's spec'd GPM. Pressures are not generally this issue, GPM is. Restrict an Allison with undersized lines or coolers or a partially plugged OEM cooler and it will let you know it right away with increased running temps, even when running unloaded. They require plenty of flow to live.

For example, a 4L80E with a cooling circuit capable of flowing 3 or 4 GPM is totally content. But run an Allison on the same capacity and you'll have problems.


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## B&B (Nov 4, 2006)

RCsLawncare;972219 said:


> Wow! Thats is some knowledge right there! But on a more serious note, I will get this done in the next week and let you know what I ended up doing. This post defiantly answered all of my and some I didn't even think about at once! Thank you for your feedback!


Good to hear you're in the clear on everything. And one additional tip that's important after doing any kind of fluid work on an Allison specifically is being sure it's at the correct fluid level once the work is done. And correct does not mean right at the full mark. When the trans is at operating temp you want the fluid level to show just at the bottom of the "HOT" range. DO NOT run it at the very top of that same hot labeled range. Most shops/dealers etc fill it all the way to the top of the HOT range thinking that this is where the level should be and this is incorrect. Doing so can lead to fluid foaming as well as the trans pushing excess fluid from the case vent. This catches many owners off guard who then thing there's a leak or something wrong with the trans. So be sure to check it once you have the service done and the trans up to temp.


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## bluefishbob (Oct 31, 2009)

Per the general, severe duty (IE plowing) it is recommended to change your fluid at 25000. normal duty at 50000. Trans flush when done correctly especially with the Allison is the best way to maintain your transmission. good bang for your buck! come see me ill flush it for ya. Gm cert tech! hah doesn't seem to mean a whole lot these days. just make sure the service garage knows what they are doing with your ally.


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## RCsLawncare (Oct 24, 2008)

I think I am going to just drain the pan pan out and change the external filter until the fluid had been changed out. The question, juts pull the plug, change the filter and fill? NO opening up the cover or messing with the internal right? Thanks for all the help guys!!


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## Q101ATFD (Oct 24, 2006)

RCsLawncare;979060 said:


> I think I am going to just drain the pan pan out and change the external filter until the fluid had been changed out. The question, juts pull the plug, change the filter and fill? NO opening up the cover or messing with the internal right? Thanks for all the help guys!!


That's correct - no messing with the internal - just remember to reuse the magnet that goes between the spin-on filter and the housing. And park on a flat surface, or slightly inclined with the drain hole low so that you get all the fluid out.


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## B&B (Nov 4, 2006)

If thats what you're going to do for now yes, same procedure as doing an oil change on the engine. Drain, change the spin on filter and re-fill.

One important tip though, when you spin the filter off look for a round magnet, will be either stuck to the filter itself or may stay stuck to the trans. If it's on the filter be sure to transfer it over to the new filter. DON'T pitch the filter with the magnet still on it. 

Happens to many guys as they're not aware there's a magnet on there.


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## stacks04 (Jan 22, 2008)

one thing to remember with an allison, even the most worn, burnt up allisons almost never exhibit any signs via the fluid. the fluid rarely burns like most ordinary trans fluids do. i have seen some very badly burnt clutches and the fluid almost always looks good. this is the main reason why i always recommend to do both filters. this way you have to remove the pan and can have a look at what might be at the bottom of the pan as far as sediment. it is a very easy thing to do especially since you can drain most of the fluid out first. the gaskets is reusable also.


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## NCat496 (Mar 30, 2008)

I have 2 trucks with Allison's in them and I love the transmission. Service is always performed on time. How long can i expect these trannys to go? I know they are bulletproof compared a regular tranny but how mush more bulletproof?


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## JustinD (Jan 14, 2008)

My buddy has a shop in MA he works on alot of Duramaxes with Allisons as well as mine, he flushes Allys all the time, in fact a few of the guys who are pushing the limit on their stock Allison are getting it done more and more. No issues with flushing an Allison.


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## RCsLawncare (Oct 24, 2008)

Still have yet to touch the transmission. Can I get the genuine Allison filter at Napa or use a Napa gold? How much is it at the dealer?


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## B&B (Nov 4, 2006)

Stick with a genuine Allison filter and don't get it from the GM dealer because the markup is crazy. Instead, either order a few online or go to a medium/heavy duty truck shop or an Allison dealer. You can purchase three filters there for what you'll pay for a single reboxed one at the GM dealer.


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## sweetk30 (Sep 3, 2006)

napa gold is a ix prem filter. 

whats wrong with them ?


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## B&B (Nov 4, 2006)

sweetk30;984654 said:


> napa gold is a ix prem filter.
> 
> whats wrong with them ?


I've fixed Allison shifting issues many times in the past by doing nothing more that replacing a newly installed aftermarket filter with a genuine Allison one. Until just recently there were issues with the inlet holes and their positioning on some of the non Allison filters that creates shifting issues due to fluid restriction to the valve body. The holes can basically be restricted by the magnet once it's installed in place in the filter. And it's only been just recently that it was addressed so there's still an easy possibility of buying the older incorrectly designed filter.

Use genuine Allison's and there's never any questions...


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## tuney443 (Jun 25, 2006)

B&B;984716 said:


> I've fixed Allison shifting issues many times in the past by doing nothing more that replacing a newly installed aftermarket filter with a genuine Allison one. Until just recently there were issues with the inlet holes and their positioning on some of the non Allison filters that creates shifting issues due to fluid restriction to the valve body. The holes can basically be restricted by the magnet once it's installed in place in the filter. And it's only been just recently that it was addressed so there's still an easy possibility of buying the older incorrectly designed filter.
> 
> Use genuine Allison's and there's never any questions...


Mike,I can't speak for other brands of filters as I don't use them,but the Napa Golds are absolutely fine for the Allison.They have 2 more holes than a GM-Allison filter plus if you look closely you will see that when the magnet is centered perfectly over the center hole,because the drain back holes are chamfered,you will see a gap between the outside of the magnet and each of the holes.When you pre-fill the filter with ATF,you can also see the fluid draining into the holes if you first put the magnet on.Having logged about 220K miles now on 3 Dmax'Ally trucks, and almost always using Napa Golds,I've never had any issues.


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## B&B (Nov 4, 2006)

You may not have had any issues Wayne but some have, including me on several different customer trucks until I discovered what was going on, so thats why I won't recommend them. 

WIX builds good filters and I use them everyday (on things besides an Allison transmission) but they missed something along the line until it was recently addressed. It is factual that if you compare their old filter (if you can find one) with the current ones they did change them. If the originals were fine why did they bother? The WIX filter rep told me specifically.....because they knew they were causing shifting issues due to fluid blockage. Had no reason to disagree with him because I experienced it first hand on several occasions myself.


It's the no name genetic ones that you really have to watch. Some of the worse ones are sold at that familiar chain store that likes everything decorated in orange. Won't mention any names.


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## tuney443 (Jun 25, 2006)

B&B;984818 said:


> You may not have had any issues Wayne but some have, including me on several different customer trucks until I discovered what was going on, so thats why I won't recommend them.
> 
> WIX builds good filters and I use them everyday (on things besides an Allison transmission) but they missed something along the line until it was recently addressed. It is factual that if you compare their old filter (if you can find one) with the current ones they did change them. If the originals were fine why did they bother? The WIX filter rep told me specifically.....because they knew they were causing shifting issues due to fluid blockage. Had no reason to disagree with him because I experienced it first hand on several occasions myself.
> 
> It's the no name genetic ones that you really have to watch. Some of the worse ones are sold at that familiar chain store that likes everything decorated in orange. Won't mention any names.


So do you know when they changed them?If I remember right,the ones I have always used have 8 holes[will check tomorrow].Hopefully,the answer is a long time ago.


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## B&B (Nov 4, 2006)

Wasn't all that long ago but I can't state an exact date. It was around last March when I spoke with the WIX rep about it, and it was done sometime before that since he stated back then they had made the changes.

But regardless, OEM Allison filters are $10.00. Why buy something else on the chance of affecting a $5000 transmission? Purchase genuine and you know what you're getting.


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## tuney443 (Jun 25, 2006)

B&B;984920 said:


> Wasn't all that long ago but I can't state an exact date. It was around last March when I spoke with the WIX rep about it, and it was done sometime before that since he stated back then they had made the changes.
> 
> But regardless, OEM Allison filters are $10.00. Why buy something else on the chance of affecting a $5000 transmission? Purchase genuine and you know what you're getting.


Well, because I get all my Napa Golds/Wix in quantity online saving quite a bit of money and believing the Ally filter was perfectly OK.As I'm sure you know,very few OEM filters are made by the manufacturer,usually they are outsourced and the real filter maker is never known,same as some engine oils.The one filter I always will use is Cat,as no company can build a better filter.I'm going to do a little more research though into this Mike, you have me worried some---now I'm not going to be able to sleep tonight.


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## tuney443 (Jun 25, 2006)

Well,you're right again Mike---I found out Wix redesigned in that timeframe with their new filter to have identical hole spacing and size as OEM.I believe I have 4 old style filters---not sure what to do now.When's it going to be my turn on being right?You don't have to answer that.


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## RCsLawncare (Oct 24, 2008)

Thanks, ill go get one tomorrow and get down to business this weekend. it looks like we might see snow Friday, don't know if it will actually accumulate though! What fluid do i need again?


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## B&B (Nov 4, 2006)

tuney443;985123 said:


> Well,you're right again Mike---I found out Wix redesigned in that timeframe with their new filter to have identical hole spacing and size as OEM.I believe I have 4 old style filters---not sure what to do now.When's it going to be my turn on being right?You don't have to answer that.


Was only doing my best to spread factual info as much as possible, doesn't matter if it was you or I who did it since there's no score keeping when it comes to helpful info being shared. But next time it can be your turn.  I know you have plenty of very factual and helpful info in your noggin too. 



RCsLawncare;985234 said:


> Thanks, ill go get one tomorrow and get down to business this weekend. it looks like we might see snow Friday, don't know if it will actually accumulate though! What fluid do i need again?


If you're only doing a drain and refill sticking with the Dex3 (as factory filled) is just fine. Just be sure not to overfill it as I described a few posts back. It's important.


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## NICHOLS LANDSCA (Sep 15, 2007)

JustinD;979566 said:


> My buddy has a shop in MA he works on alot of Duramaxes with Allisons as well as mine, he flushes Allys all the time, in fact a few of the guys who are pushing the limit on their stock Allison are getting it done more and more. No issues with flushing an Allison.


I doubt he is FLUSHING them he is EXCHANGING the fluid in them. Huge difference between the two, but commonly called both for the same thing.


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