Hey, was just at the tranmission shop and asked the guy how long the tranny should go for on my 2003 GMC SIERRA truck. He said 60, to 90,000 miles, if you dont get it flushed. He said if you change it every 30,000 miles, from what he has seen it will just keep going and going. If towing every 20,000. So your thinking... "is he right?" Well my brother hadnt done his on his 2002 Sierra for just about 90,000 miles and guess what went. Not even 3 days after I told him this! 70 bucks to get it done is nothing when your looking at a whole new tranny if you dont. Pass it along.

I guess I just baby my truck to much I get my tranny oil changed every 30000 Kilometers and have it flushed every other time.

Do not ever flush a transmisson!It is a big no no.The dirt gets pushed back in during a flush with the machine and where does the dirt go?The dirt gets pushed into the valve body and gets stuck in there.My father knows a guy that has his own transmission shop that does valve body cleanings because someone had their transmission flushed.

All I hear are horror stories about flushes with the machine and I have replaced one transmission so far because it was flushed.It was 4 quarts low and luckily it moved,it started acting up and replacing the transmission was the only choice.The flush machine uses MORE fluid and mixes with the old fluid which is a bad idea.Replacing the fluid and filter is the best thing to do to an automatic transmission.If you want a better flush that is cheaper,remove the lower transmission line(from the Radatior) and put a hose on the line to a bucket or pan.Start pouring fluid in while running without running out it dry until it is clear.This is the better way,removes the dirt and crud and does a lot better job than the machine

Do not ever flush a transmisson!It is a big no no.The dirt gets pushed back in during a flush with the machine and where does the dirt go?The dirt gets pushed into the valve body and gets stuck in there.My father knows a guy that has his own transmission shop that does valve body cleanings because someone had their transmission flushed.
That sounds like a case of hear say evidence there.

It is not the flushing or transmission service.
It is the people that do not service them and then when the transmission is on it last leg.
Gets a flush in the hope that the flush will flush there trouble away.
People that service have a lot less transmission trouble that people that do not.

MT-2500 is right. A trans flush is routine service, not a cure all. There are a lot of factors in transmission failures. Maintainence, use, abuse, faulty parts or workmanship, and the trans that just plain goes out. Maintainence will help anything last longer (until it meets is fate).

03 z71 5.3 get mine flushed and filter at around 30,000 40,000 miles its alot cheaper then a new tranny

Why do we keep digging up old threads?

Old threads get dug up because when someone asked a question, people always say "try a search" So they try a search and come up with these old threads and have question to go along with them, i think its a good idea to revisit old threads if someone has some new info on an old topic.

I had a company van that had over a 100K miles when I got it and the trans was slipping badly...the trans fluid looked like dark brown honey...I had it flushed at a quicky cheap oil change place and it ran like new. If it was my van replacing the filter/fluid would have been a better route. The company was super cheap and I barely got the flush out of them.

The pan-drop change is the worst thing you can do for a transmission (even with the "filter"[screen] replacement), especially one that is electronically shifted. The 1/3 to 1/4 new fluid breaks down the gum and varnish, and then you get the problems wafredrick was talking about. A flush, when done correctly, gets every bit of "dirt" (and 95%+ of the old fluid) out of the transmission.

I'm not saying I compleetely agree with 30k flushes on a truck. Perhaps on a small inadequately cooled transaxle... at 30k on a truck the fluid is still bright red.

Here is a REAL flush and it is better than the machine,a line flush.The advantage with the line flush is you use less fluid and you CAN see the condition of the fluid.Remove the bottom line from the radatior hooking it up to a hose which is pointed to pan.Start pouring in fluid while the vehicle is running making sure you do not run the transmission dry.Stop when it is clear,you are done and reconnect the line to the radatior.This is true that I mentioned,my father saw a valve body cleaning done at this transmission shop we know.Change the fluid and filter,it is the best thing to do and I have never seen a problem after a fluid/filter change.I seen fluid that was way overdue about 6 monthes ago with about 300,000 miles on it,a 1992 Dodge with a Cummins diesel and a flush would not fix it.Changed the fluid and filter,transmission shifted better and that was the complaint.I will not give out the Tranmission shop's name or their phone number.The trans filter is like an oil filter,traps dirt and crud.

The pan-drop change is the worst thing you can do for a transmission (even with the "filter"[screen] replacement), especially one that is electronically shifted. The 1/3 to 1/4 new fluid breaks down the gum and varnish, and then you get the problems wafredrick was talking about. A flush, when done correctly, gets every bit of "dirt" (and 95%+ of the old fluid) out of the transmission.


I would have to disagree, the reason a pan drop is done is to replace the filter and then only add enough fluid to bring the level up to specs. In my experiance, when transmissions with higher miles are flushed and 10-12 quarts of new fluid is added, the high levels of detergents in the new fluid will degrade the adhesive that holds the clutch material to the plates and cause a clutch fauilure.
I never recommend a flush to customers with higher mileage vehicles nor to a customer who has some minor trans problems they believe will be remedied by a flush

Agreed and GM powertain engineers do not recommend it either.

I would have to disagree, the reason a pan drop is done is to replace the filter and then only add enough fluid to bring the level up to specs. In my experiance, when transmissions with higher miles are flushed and 10-12 quarts of new fluid is added, the high levels of detergents in the new fluid will degrade the adhesive that holds the clutch material to the plates and cause a clutch fauilure.
I never recommend a flush to customers with higher mileage vehicles nor to a customer who has some minor trans problems they believe will be remedied by a flush

GMMerlin
Right on there.
Flushing is not the way the good old factory repair manual says to do it.


To Flush or not To Flush ?
Just like Kenney Rodgers said you have got to know when to fold and when to hold.
If the fluid has high mileage 100K or over or is real dirty you had better hold.
On a trans that has had good regular service at 50K or sooner a flush is good.
But be ware of jiffie/quick/wallmart /fast lubes that offer power and fast flushes.
They have abused and over rated the trans flush.
They have a habit of using one fit all fluid out of the same barrel that fits all.
They just throw in a bottle of additive to make it fit all. Or worse they pitch in a bottle of cleaner or dope in it that can do more harm than good. And will tell you the filter does not need changing with a flush.
Just remember that all new fluid makes a high detergent cleaner that will break loose all varnish and dirt and grit in the trans and drop it in valve body and solenoids.
Always change the filter and go easy on or use no dope and cleaner.
Adjust/check the bands and linkage on the trans that have bands and adjustments.
Always use the trans fluid the trans/manf calls for. And be aware that some manf have changed the type of fluid specs since the trans was manf.
Some fords have changed the specs and a lot of cry/dodge have gone to the newer type of fluid on their trans service.
The only exception to total flush rules is.
Some year of fords and certain ford transmissions have a tsb and require a total complete trans flush to cure trans shifting problems.
Some as low as 30K
If a person does not have a flush machine a old 5 gallon bucket and a couple of rubber hoses to connect to the cooler lines and with the other end in the bucket will make a good flush machine. Just put the hoses in the bucket and start the engine and start pouring fluid into the trans until the fluid running into the bucket gets good and clean.
It usually takes 16-20 qts. To get a good flush.
Flush or No flush always service the trans filter and trans on a good regular basic.
People that keep the serviced have a lot less trans problems.
MT

I bought this truck with 77,000 on it and have no idea if the fluid has ever been change. I want to change it but don't know which method to use. Is 77,000 considered high mileage. The fluid looks and smell good.Should I drop the pan or have the dealer pump it out or do both.

Do the line flush instead of the machine if you want to flush and change the fluid & filter too.

No 77K is not real high mileage.
If yoiu are not sure what to do get some good repair information like All data or a factory repair manual.
They have the mantiance sceduals and procedures in them.

Regular service for the transmission is usually pan drop and filter around 50K.

Yours may or may have not been done.
If you can check with the dealer that sold the truck new.
He may have mantiance and warrant records on it.

If mantiance is not known than a pan drop and filter change is the best way to go on it.

Only problem is dexron 111 is not made any more and may be hard to find.
Do not use the multi purpose stuff.

Gm say says to go to dexron 4.
But I am from the old school if it has had dexron 111 used in it I like to stay with it.
If you can not find dexron 111 Carquest and some other parts places still have mercon/dexron the stuff dexron 111 replaced.

Why do we keep digging up old threads?
Good question. It's usually done by "newbies" unfamiliar with the guidelines.

Old threads get dug up because when someone asked a question, people always say "try a search" So they try a search and come up with these old threads and have question to go along with them, i think its a good idea to revisit old threads if someone has some new info on an old topic.
It's a good idea to revisit old threads, HOWEVER it is not a good idea to resurrect them. If you have new info to add , our Community Guidelines ask that you start a NEW thread and link to the old one if necessary.
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