Transmission fluid change

[Disforcfc]

Hello,

My truck has about 154k miles on it. I bought it used this year. I have no idea when the last time the trans may have been serviced. I want to do a simple drain and fill. I do not want to do the forced flush one that the dealers do, i have been told by numerous mechanics and transmission techs that once its past 100k to not do that on auto transmissions.
My mechanic that i usually go to does not want to even do the drain and fill, he told me that even that can lead to problems on these older transmissions.
I have already bought the ATF fluid, the filter, replacement magnet and gasket. I just wanted to come on here and ask people what they thought and the exp they have had with their trans on their trucks

Thanks
Dan

 

[ygmn]

yes you can read about both sides of this coin.

some say replacing will loosen up gunk in tranny an end up clogging passages or doing more harm then good

Others say that is all false and fresh fluid and filter is the way to go for long life.

Best you read on here experiences of others... and you will find it goes both ways and problems go both ways.
Tranny service as not caused and caused issues - who to believe?
doing nothing causes and does not cause issues - who to believe?

Here is issue:
Tranny is at its limit with these trucks, engine and drivetrain.
Soem have had tranny failures while others have not.

Is it how we drive?
How we have truck setup with large or small tires?
IS it environmental - Does not like cold or hot?
Is it fate?
Is it pure chance?

Mine tranny is all original from being built in 2001 - no fluid change or added ever
Has about 175k miles not driven as much as before due to second car but she still works for her monthly gallop.
also 2wd Z66 w/3.73 gears

Question is how does she run now?
what is fluid condition now? maybe send sample out for testing??

Goos luck !

 

[EXT4ME]

When I bought my 2004 AWD EXT with the 4L65E transmission, the truck had 116K miles on it and no maintenance history.

There is some evidence that the EXT may had been heavily used, if not abused, during it's earlier life.

The transmission failed on me at 125K and was rebuilt.

I later had an unexpected transmission fluid change some time after that when one of the transmission cooler lines popped off the side of the transmission going down the freeway, resulting in an instant and near total loss of fluid.

I had the truck towed back to my mechanic's shop.

I went ahead and had my shop replace the filter at that time and refill with fresh fluid.

No further fluid service done since and the truck currently has 236K miles on it with no signs of trouble, so far.

I bought my 2003 Avalanche Z-66 2WD with the 4L60E transmission with 240K miles on it.

I know the previous owner that had bought the truck new and they provided me with the truck's complete service history.

They had a lot of regular maintenance done over the years, but a transmission fluid service does not seem to be one of those items.

Since the Avalanche does not have the factory installed auxiliary transmission fluid cooler like the EXT does, I installed a Tru-Cool - Max LPD47391 47391 Low Pressure Drop Transmission Oil Cooler, which I recommend to anyone that does not have an auxiliary cooler.

I primarily installed the Tru-Cool as a proactive step for when the old transmission in the Avalanche finally does go bad and gets it's rebuild.

The Avalanche now has 280K on it with the Tru-Cool having been installed for most of the time I have owned the truck.

Knock on wood, I sense no impending trouble from the transmission at this time.

I do not intend at this point to mess with changing any fluid or filter in this transmission.

I feel it has had a good run and when the time comes for it's eventual rebuild, I may try to change fluid and filter from that point forward.

No need to tempt fate, as it were.

 

[Randy]

IMHO, dropping the pan, changing the filter and topping off the fluid will not harm anything. Your only adding 3-4 quarts and will not break anything lose and at the minimum it will put some fresh fluid in, and you will be able to judge the condition of your trans, if the pan has a small amount of material, you can probably judge that it hasn't been abused too much. On the other hand, if it's full of plate material and smells burned, then you can probably figure on rebuilding/replacing in the future, the 4L60's are not that strong of a trans unless modified and I would want to know.. Alot of people have had trouble with them here, It's up to you..

I do not ever advise on the dealer's method of flushing the trans, from what I understand they back flush under pressure through the trans cooler lines and that's where things can come loose and damage the trans..

The method I prefer is what's called a "Fluid Exhange" you take the top cooler line off and connect it to a machine with two reservoirs, one with new fluid and one to capture the old dirty fluid. When you start the vehicle dirty fluid coming from the top radiator connection for the trans (return line to the trans) goes into the holding tank on the machine and at the same time the new fluid goes in and back the trans, circulating the new fluid though the trans and torque converter. The machine has clear reservoirs, so you see the dirty fluid coming out. The hose they connect is clear so when you see the dirty fluid turn to clean red you know that nearly all the old has been removed. This method uses the same circulating direction and pressures that your trans use so the only thig that happens is you get new fluid.. Then drop the pan and change the filter if you want..

Although my AV has the 4L85E and a different trans I've done mine this way every 50,000 -75,000 miles and have almost 290,000 on the original trans. One thing the owner's manual says that you can change the trans fluid every 100,000 miles.. But it also says to change it at 50,000 if you drive in heavy traffic or regularly tow anything, so everybody overlooks this and think it's okay to do it at 100k or more... My recommendation is not to follow that and change it every 50,000-75,000 miles.

 

[Disforcfc]

IMHO, dropping the pan, changing the filter and topping off the fluid will not harm anything. Your only adding 3-4 quarts and will not break anything lose and at the minimum it will put some fresh fluid in, and you will be able to judge the condition of your trans, if the pan has a small amount of material, you can probably judge that it hasn't been abused too much. On the other hand, if it's full of plate material and smells burned, then you can probably figure on rebuilding/replacing in the future, the 4L60's are not that strong of a trans unless modified and I would want to know.. Alot of people have had trouble with them here, It's up to you..

I do not ever advise on the dealer's method of flushing the trans, from what I understand they back flush under pressure through the trans cooler lines and that's where things can come loose and damage the trans..

The method I prefer is what's called a "Fluid Exhange" you take the top cooler line off and connect it to a machine with two reservoirs, one with new fluid and one to capture the old dirty fluid. When you start the vehicle dirty fluid coming from the top radiator connection for the trans (return line to the trans) goes into the holding tank on the machine and at the same time the new fluid goes in and back the trans, circulating the new fluid though the trans and torque converter. The machine has clear reservoirs, so you see the dirty fluid coming out. The hose they connect is clear so when you see the dirty fluid turn to clean red you know that nearly all the old has been removed. This method uses the same circulating direction and pressures that your trans use so the only thig that happens is you get new fluid.. Then drop the pan and change the filter if you want..

Although my AV has the 4L85E and a different trans I've done mine this way every 50,000 -75,000 miles and have almost 290,000 on the original trans. One thing the owner's manual says that you can change the trans fluid every 100,000 miles.. But it also says to change it at 50,000 if you drive in heavy traffic or regularly tow anything, so everybody overlooks this and think it's okay to do it at 100k or more... My recommendation is not to follow that and change it every 50,000-75,000 miles.

I heard exactly the same with the dealer method, def not gonna do that.

Maybe i can find a trans ship to do that fluid exchange method so i could see, or maybe first time ill just do the trans drop and do a self inspection. mine has 153k miles and i have no records of service. I did the oil and air filter as soon as i got it and used an engine treatment that you added to oil and gas tank and run on idle for 20 mins.
It has driven good since i got it but i do live in la and i am in traffic just so cal in general so i will follow that 50-75k guideline. thanks for the info

 

[Randy]

Some oil change places have them...

 

[07AVSS]

You will be fine doing a pan drop filter change and new fluid with no flush shall we say. Will not hurt a thing.

My 4L60 in my 07 went 260K miles with one pan drop filter and fluid change at likely 200K miles. Worked flawlessly
the whole time. I had to pull and rebuild the engine at 260K and had the trans redone since it was out anyway. Guy that
rebuilt it said it basically looked new inside with very little signs of wear.