trans fluid... to change, or not to change

[gmchevroletruck]

A tip I received in another forum, from a guy out of state who works in a transmission service shop, said that "if the fluid is brown, or smells burnt, do not change it - you'll remove the friction material that is floating around in there which has already done damage to the discs, and will cause slippage. Have seen people do this, and not make it out of the shop." He also went on to quote instances of used car dealers putting sawdust and similar things into ATF on known bad transmissions to prevent slippage long enough to make the sale, etc.

Ok, now for my specifics: 138k, no clue what the prior transmission service history was prior to 88k, but I have not changed it from 88k to the current 138k, and have towed about 3000lb almost daily (full size pickup - Chevy with 4L60E transmission). Service manual says change every 60k, or every 30k when towing. The fluid seems to smell burnt to me, but is a nice red color, with no cloudiness or visible signs of metal on dipstick.

On to the questions:
1) Has it been "too long", to where, changing the fluid would cause more harm than good? (transmission has slipped on me maybe 3 times, very slightly, and the instances were spread out over a month or so)
2) If you recommend a change, how would you do it? Drain and fill? Drop pan and replace filter?

and the final question...

3) What is the final word on transmission flushes? I've heard conflicting things - "it's great", and "it's risky, and can do more harm than good".

I'd rather err on the side of caution with all of this, but would like to get some clarity on what that is exactly.

Any thoughts?

 

[Herz]

Is it a auto or manual? and 130k isnt "too" bad if it is auto. if its a standard just drain and fill with better fluid.

dont flush IMO can dislodge something and re-lodge it where you dont want it too be.

 

[gmchevroletruck]

4L60E is the 4speed electronically controlled auto

 

[Turk]

I know these transmissions well - had 3 of them with high mileage and a good share of hauling and towing.

1) No, it hasn't been too long whatsoever. From 88k to 138k? Absolutely change it!

2) Full fluid changeout if the filter has been change at least once. If not, change the filter also.

3) I have the full changeout flush done after a one time filter change and had zero issues.

 

[postjeeprcr]

Originally Posted By: gmchevroletruck
A tip I received in another forum, from a guy out of state who works in a transmission service shop, said that "if the fluid is brown, or smells burnt, do not change it - you'll remove the friction material that is floating around in there which has already done damage to the discs, and will cause slippage. Have seen people do this, and not make it out of the shop." He also went on to quote instances of used car dealers putting sawdust and similar things into ATF on known bad transmissions to prevent slippage long enough to make the sale, etc.

Ok, now for my specifics: 138k, no clue what the prior transmission service history was prior to 88k, but I have not changed it from 88k to the current 138k, and have towed about 3000lb almost daily (full size pickup - Chevy with 4L60E transmission). Service manual says change every 60k, or every 30k when towing. The fluid seems to smell burnt to me, but is a nice red color, with no cloudiness or visible signs of metal on dipstick.

On to the questions:
1) Has it been "too long", to where, changing the fluid would cause more harm than good? (transmission has slipped on me maybe 3 times, very slightly, and the instances were spread out over a month or so)
2) If you recommend a change, how would you do it? Drain and fill? Drop pan and replace filter?

and the final question...

3) What is the final word on transmission flushes? I've heard conflicting things - "it's great", and "it's risky, and can do more harm than good".

I'd rather err on the side of caution with all of this, but would like to get some clarity on what that is exactly.

Any thoughts?


First question, I do not believe it has been to long, I would prefer new fluid with all the additives it comes with instead of old fluid with worn additives.
As for your second question, I am not sure about your 4L60E but to do a drain and fill on mine I would have to drop the pan as there is no drain plug, so if yours is like mine and if you have to drop the pan then you might as well replace the filter at the same time.
Third question, Now with a flush they pump in new fluid which pumps out the old fluid so if "something" was "lodged" it should get pushed out, I do not see whatever maybe "lodged" just getting stuck somewhere else if all the old fluid is supposed to be replaced by a flush.

 

[ZZman]

A flush is O.K. Using flush chemicals could be an issue.

Change that fluid.

 

[pbm]

I would D&R with a new filter and use a good ATF like Mobil 1, Amsoil etc. I would NOT flush it.

 

[doitmyself]

I think there might be some machines still around that do a pressurized flush, some even claim there are ones that back flush. Others advertise using chemicals. I would avoid these.

If a shop has a T Tech machine, it gently replaces the fluid as your transmission pump pushes it out. Safe in my opinion. You also have the diy cooler line fluid exchange.

 

[SteveSRT8]

Almost no one uses the "push' setups anymore.

Look for a passive fluid exchange. Do the exchange first and then drop the pan and clean things up in there, new filter, etc.

A proper system uses your own trans pump to move the fluid, so the filter is still in the loop.

The worst 4L60E in our entire fleet ran over 150k miles. Most never break with proper maintenance. The 4L65E seems bulletproof.

 

[TheOak]

You could always pump out the transmission fluid too by getting a pump and snaking a tube down the transmission dip stick tube if there is no drain plug.

Question:

I purchased a used 2007 Yukon XL. How would I tell what transmission I have? Obviously it is a 4 speed automatic. But it it a 4L6 what? Is there a way to tell?

 

[JTK]

I've had several 4L60Es as well. If there's no issues prior to the ATF swap, there shouldn't be any after.

Joel

 

[ET16]

Originally Posted By: TheOak
You could always pump out the transmission fluid too by getting a pump and snaking a tube down the transmission dip stick tube if there is no drain plug.


That's what I usually do.

 

[gmchevroletruck]

Originally Posted By: tpitcher
I know these transmissions well - had 3 of them with high mileage and a good share of hauling and towing.

1) No, it hasn't been too long whatsoever. From 88k to 138k? Absolutely change it!

2) Full fluid changeout if the filter has been change at least once. If not, change the filter also.

3) I have the full changeout flush done after a one time filter change and had zero issues.

Not sure the history on the truck....it may have never been changed for all I know. I bought it with 88k, and all I know for sure is that it hasn't been changed between 88k and now (138k). How long it had been, if ever, before that, I have no idea...

 

[Herz]

just change it.

 

[Ibrahim]

MY FRIEND! Do Not Flush! DO Not Please!

Drain, Clean The Pan & Magnet, Fill

 

[ionbeam22]

Certainly you should change it.

The deal with "flushes" is that the word "flush" gets used to describe all sorts of services done with a TF exchange machine.

The "service" you don't want, is one where they use chemicals to clean the transmission. The chemicals are a black box, and in some cases do too much cleaning or harm the friction materials.

Another "service" you don't want is the use of additives into a basic Dex/Merc III fluid. They won't convert it into the proper fluid. There is no savings in using low quality transmission fluid.

There are two ways to change the transmission fluid, using an exchange machine, and dropping the pan. If you want to have the filter replaced, you will need the pan service done.

 

[FZ1]

When in Doubt;Change it Out.

 

[demarpaint]

I'd change it. If you don't have a drain plug, get a small suction pump and get as much old fluid out as possible before dropping the pan. You'll thank me later. Drop the pan, clean it out, change the filter, and add the proper amount of new fluid. If the transmission was properly filled before you start measure how much fluid you get out. Add back a tiny bit less and top it up as per the OM instructions for checking the transmission fluid level. I've been doing it this way for a very long time, and it makes things a lot easier.

On a side note I got a quote for $90 to drop the pan, change the filter and gasket and refill the unit. I might just go for it since if there are any pan gasket leaks it won't be my problem, especially during the winter months.

 

[fdcg27]

I would drop the pan, clean it and replace the filter.
Refill with the correct fluid.
I have done this with a few >100K automatics we have had over the years and I have always had good results.
Even this partial change will likely yield noticeably improved operation.
I have read here and there that if a pan drop and partial change brings a failure, the failure was coming anyway.

 

[JohnBrowning]

Alqways change? What tpe of knuckle head would not change their transmission fluid and expect long life?