I've heard from more than several people that if you have your transmission flushed, the fluid changed, or mess with it at all, when it hasn't been done after X amount of miles, you could ruin the transmission.  I guess it has something to do with disturbing metal shavings in the system?  I my duramax has 2 filters in the transmission and the dealer says that they don't do flushes.  They take off the pan, change the filters, and add new fluid.  Am I going to ruin my truck?  It's an 02 with 62,000 miles.  The tranny has been perfect, and the fluid seems fine to me.  I am having the truck inspected thoroughly for trail riding season, and the transmission is a key component.  What do you think I should do?  Maintain it, or leave it be?  A new transmission will really put a dent in my trail riding funds.

Amanda

If you don't maintain your transmission, the repair costs will definitely leave a hole in your wallet.

The pan should be dropped, and all the fluids drained including the torque converter. Some converters have drain plugs, others require the flushing to evacuate the old fluid. New filters and new synthetic transmission fluids are then installed. If this is done every 50k, it's likely your transmission will provide trouble free towing for the life of your vehicle.

A towing vehicle experiences a great amount of heat and stresses within the transmission. If older fluid is allowed to remain, it will break down sooner under the high temperatures. That will create even more heat, and now you have a cycle in which the lubrication is finally compromised. When something ultimately fails, and a malfunction occurs, it is too late. The internal transmission components are irrevocably damaged, and no amount of fluid changes or additives will repair the damage. Your only recourse is then to open your wallet and dig very deep.

Heat is the killer of transmissions, and towing exacerbates the problem. Using the best fluids available, will increase its life span by lowering the friction and the resulting heat. Proper maintenance will result in lower operating costs and fewer breakdowns. The reliability of your vehicle's drive train is directly responsible for your traveling well being. It's a win win situation. Take care of it, and it will take care of you.

Gard

  Have your Allison 1000 series flushed, that gets all the fluid change out including the torque converter, the cooler and cooler lines. You only change 7 quarts when you drop the pan, you change out about 20 quarts doing the flush. After the flush, change the spin on filter. I Change the spin on filter and fluid every 25,000 miles, for severe service, pulling trailers etc. or change it at 24 months.. Change fluid and spin on filter every 50,000 if you're chasing kids and groceries. Pull the pan and change the internal filter at overhaul. The internal filter is not so much a filter, it's more like a strainer.

http://www.allisontransmission.com/service/changeinterval/questions.jsp?model=1000&voc=HS&type=1k2k

I've heard from more than several people that if you have your transmission flushed, the fluid changed, or mess with it at all, when it hasn't been done after X amount of miles, you could ruin the transmission. I guess it has something to do with disturbing metal shavings in the system?

I've been told that too and never understood the logic.  By flushing the system and changing the filters you'd be removing the shavings that would cause the damage.  Right?

Invariably when the pan is pulled for the first time, you will find metallic pieces laying about. The filter or screen below the valve body prevents these from entering the pump and circulating throughout the system. It's a good idea to change all the filters, remove the pan, flush the converter and add new fluid.

gard

The word 'flush' is widely used when 99% of the time its a fliud EXCHANGE using a BG machine.Basically a bladder with new fliud and the trans/engine itself is just pumping out old while the bladder pushes in new fluid.No FLUSH to it.Best thing to happen to a auto trans since its invention.I've handled I bet THOUSANDS of drop the pan,change filters and hook up and EXCHANGE new fluid in and old out with vehicles that have 90k plus on them with nothing but good results.Gm,Chrysler,Mazda,Isuzu,Nissan etc. Usually makes a differance in trans operation that is slightly noticeable where as filters only and make up fluid added to old fluid does not.Just ask if its a FLUSH machine(they are a FEW out there) or a FLIUD EXCHANGE which most all are and get it done.Best maintenance money you can spend.Do a SEARCH on BG Fluid Exchange and trans FLUSH and see what reading you find.There is a way to do such in a driveway ho I wouldn't as it is a pain to do.I know shops that if YOU supply the fluid will swap the fliud(exchange)for a little as $35 bucks to $75 and or do the filters,fliud etc.and pay up wards to $300. Do some shopping at GM service centers and see what they charge.Use the PROPER fluid on that Allison.

Good grief.  Does nobody read the owners manual any more?

As retento has already posted, if towing frequently 25K/ if not 50K; pull the drain plug, change the spin on filter and clean the spin on filter magnet.  Do NOT pull the pan, thats a waste of time, the internal filter only gets changed at overhaul.  It is highly unlikely there will be metallic anything laying around in the pan to begin with.  Any metallic debris will be stuck to the magnetic tip on the above mentioned drain plug....IF it got past the magnet on the spin on filter and then the filter itself. 

The Allison does not need "flushed", "exchanged" or any other old school nonsense.  While those methods are great for lighter duty transmissions they are not necessary for the Allison.  Between the drain plug magnet, spin on filter magnet, the spin on filter itself and the internal filter this is one clean running, easy to service transmission.  Damn, its almost like somebody thought this through.............

So to answer your question, yes it needs changed if you have not done so in 62K.  Just follow the owners manual, millions of miles have been put on Allison transmissions that way.

Some people will never be comfortable when things change.  Thats fine, its your time/money.  Im going enjoy the progress the automotive industry has made.

Seems like Im the one embracing change.  I dont remember spin on filters on trannys 20 years ago when I HAD to change out all the fluid???  This "new" application of technology is what allows superior performance with minimal maintenance.

Cripes, I remember changing oil every 3K, do you still do that too?

So in those years being an auto pro you never became aware of Allison?

I remember when it was announced Allison would provide trannys for GM, it firmly grabbed my attention.  I had sworn off auto trannys for towing many, many years ago.  I was still hesitant when I purchased the GMC, and have kept an eye on the "scene" since then.  Allison has held up their reputation, providing very reliable equipment.  They know how to build and maintain a transmission.

You appear to be a fan of synthetics.  Are you familiar with those guys who run synthetics and the bypass oil filtration systems?  Some of them extend their engine oil change intervals to 30K plus, changing only the filter and sending oil in for analysis.  The oil is kept clean by the filters and new additives are added by the make up oil from the filter changes. 

Sort of the same principal with the Allison maint.  The fluid is kept 'clean' by the spin on filter and magnets, and ~1/3 of it is renewed along with the spin on filter at regular intervals.  Assuming your 1500 does not have an actual filter (not counting the 'screen' in the pan) then I would agree with an exchange for that tranny.  Due to the fact changing only ~1/3 of the fluid in that situation you would be dumping a little clean fluid into a lot of dirty fluid.

Hounddog - I have to ask... Older trannys, dropping the pan was the only way to do everything you needed to do. They weren't filtered like these Allisons, so my biggest question here is why? Do you drop your oil pan when you change your oil, or concern yourself with a flush of the system for your motor oil? There inevitably is some oil left and you are mixing old with new there. Explain to me the difference.

edited to add; If you were to flush an Allison, aren't you flushing the new fluid through the old filter, or if you change the filter first, the old fluid through the new filter?

I don't own an Allison, so my comments will be generic.

"Do NOT pull the pan, thats a waste of time, the internal filter only gets changed at overhaul.  It is highly unlikely there will be metallic anything laying around in the pan to begin with.  Any metallic debris will be stuck to the magnetic tip on the above mentioned drain plug"

When the pan on my transmission was pulled to modify the valve body and install the temperature sending unit, there were several pieces of material laying in the pan. Not all were ferris/metallic. This is not an uncommon situation, and usually will not effect the opperation of the transmission. Many of the transmission parts and components are not steel. The in pan filter or screen usually prevents these materials from entering into the pump. Many of these materials are the result of insufficient flushing of the parts after the machining/manufacturing process. On one of my cars, when the pan was pulled, the filter was found laying in the pan. That's why the first oil/filter change is important for a new vehicle. You cannot depend on magnets to remove all the foreign materials in your oil. Allison recommends a filter change after the first 5k on new and rebuilt transmissions.

The newer vehicles have higher HP and torque figures, are pulling increasingly heavier loads and the transmissions are being adapted to engine braking and vehicle retardation on hills. All this additional stress greatly taxes any lubricant, synthetic or otherwise. It is only in the owner's best financial interest to maintain his vehicle in a timely fashion, and not ignore things when they are going well.

Allison builds remarkable transmissions. Like any other piece of machinery, they are not infallible. A buddy of mine purchased a new pusher diesel RV. On his inaugural trip south to see a Nascar race, his pride and joy spent the better part of the week at a repair shop with a failed Allison transmission.

"fluid is kept 'clean' by the spin on filter and magnets, and ~1/3 of it is renewed along with the spin on filter". I didn't realize that the spin on filters held over a gallon of fluid.

Gard

This is correct. Partially. Allison recommends that the spin on be replaced.

I do own two Allisons. This thread got me curious, so I have spent most of the morning researching exactly this. Allison does not recommend fluid exchange machines. They clearly state this.

http://www.allisontransmission.com/servlet/DownloadOnDemand?ApplicationID=155&DownloadID=5&Preview=1 They also do not recommmend dropping the pan and changing the internal filter with the exception of an overhaul.

Well thats a wonderful piece of generic info, maybe someone will find it useful.  However this thread was originally about the Allison transmission.  Perhaps you could address Terri's question, with your obviously vast generic knowledge? 

As for the spin on filter holding over a gallon of fluid, you know better than that.  Maybe if I had said; "The fluid is kept 'clean' by the spin on filter and magnets.  Also during service ~1/3 of the fluid is renewed as well as the spin on filter being changed." you would not have become confused?

No one is claiming the Allison is "infallible", I wont even claim its any better than the newest trannys from Ford and Dodge.  Only pointing out that it does not need the extensive maint that the older models required.

My generic knowledge includes the fact the most spin on filters hold approximately one half to one quart of fluid. Based on its maximum capacity, the fluid volume in the filter would then equal out to approximately 7.7% of the transmission's total quantity.

Yet it was stated that a third of the fluid would be renewed with each filter change. If that were true, does it mean that the transmission only has a three quart capacity, and all the published specifications are in error?

This is sooooo confusing

Still confused?  Boy, I hate that.  Maybe you could attempt to decode my cryptic message and re-write it with your generic knowledge so other people could understand?

 I just serviced my Ally last summer, so I dont really want to do it again just for a DIY post with pictures.

Good luck with you quest to understand the Allison.

As for the person's question that started the thread, No a fluid exchange will not brake a tranny. If the tranny brakes after it, it was already bad. Very very few folks flush anymore.  They are all fluid exchange machines. I would recommend changing the filters and doing a fluid exchange. You are over what I would recommend for the first change. I do mine every 30,000 miles or sooner. Fluid is cheap. If that Ally craps out it is going to be expensive to rebuild due to the design and name.  Some folks just like to runoff at the mouth. They have no imperical data to the applicable issue to offer any relevent information. I see and hear it everyday so much that I get sick of it. Just do what you are comfortable with. No biggy, but get it done real soon and don't put it off.

Did you not read the link posted by Tresvolte?  Technically I didnt either, but it no doubt refers to the fact some exchange machines can not keep up the the Allison and can BURN up the transmission.  As such Allison DOES NOT recommend the process.

Anyone else notice a pattern here?  Seems like the guys who dont have an Allison keep screaming do the flush, the guys who do own the Allison are following Allison's instructions.