2 6l90's toast close to the same mileage?

[Newman88]

So I bought these 2 trucks brand new in 14, both are 2014 GMC 2500HD's 6.0 6l90's. Changed tranny fluid right at 100k the next service for both trucks was at 200k as all my other older GM trucks that have always had 100k complete cooler line drain no trans pan filter change.

These two trucks had the same symptoms, delayed reverse and 3-4 gear slam, both have burnt oil and lots of metal flakes in the pan, both hauled a max of 2500lbs most of the time. As all my GM trucks they receive a diet of STP Dexron IV, one died at 190k the other at 218k. I know there are some variables but both going out close to the same mileage makes me wonder what is really going on here, the older 4l80 trucks have 350k+ miles on stock trannys including the stock trans filter and loaded close if not more than these newer trucks and have held up great.

So my question was it the oil at fault?
Driver?
Maintenance?
Or is the 6l90 just a bad tranny?
I read in the GM forums where guys are swapping out the 6l90/80 transmissions in favor of the 4l80 because it has stronger parts? I don't know much about transmissions so please enlighten me trans guru's.

 

[spasm3]

PM member clinebarger .

 

[ls1mike]

100k Service is way too long for a 6L90E. Usually way to long for a 4L80E.
I just did a pan drop and filter change on my 17 with 30,000 miles on it.
Recommend service for these is every 45,000 miles.

You waited way too long. The 6L90E is a good unit as is the 6L80E

While certainly not a 4L80E, it is a good unit when properly maintained.

The guys doing the swap are few and far between and they are guys making more power or being stupid with the 6L90E.

What do you do with these trucks?

 

[Macsignals]

As Mike said the interval for these is 45K. These certainly don't seem to be as immune to abuse or longer intervals as the four speeds seemingly were.

Dealer did my 6L80 at 43K. Currently has 54K. It shifts... When it wants to sometimes and will slip its way through 1/8 mile while trying to decide what gear to grab or until I can make it over to the shoulder. But I'm pinning that on this particular transmission and not them as a whole.

Swapping to a 4L80E just sounds like a trainwreck in the making unless you have every single part, bolt and ounce of fluid lined up for the job. And even then it sounds like a headache. I say it's time for two new 6L90s and 30-45K changes this time.

 

[Chris142]

100k is too long. Lack of maintenance killed them. I would put a drain plug in them if they don't already have one. Then do a drain and fill every other oil change.

 

[ls1mike]

The beauty is they have a drain plug and the pan is easy to drop.

If you drain the pan you get about 6.5 quarts out. The complete 6L90E system holds 12.4 quarts.
You can do a pan drop and filter swap every 10,000 miles and never have dirty fluid.
Easy Peasy.

I hate to say it, you murdered them.

 

[rubberchicken]

Or perhaps the mechanic stroked the job , and never actually changed the fluid ?

 

[AC1DD]

Originally Posted by rubberchicken
Or perhaps the mechanic stroked the job , and never actually changed the fluid ?


Winner winner chicken dinner...Happens ALL the time, I'd say much of the time...when it comes to shops changing fluids they are ripping people off most of the time.

 

[maxdustington]

100k miles for work truck ATF in NM?

 

[Snagglefoot]

I had a pan drop and flush done every 50,000 miles. Now I'm swapping 3 quarts once a year through the fill tube. Just hit 200,000 miles so I guess I'm not ahead of the OP. I'll have to wait and see. I plan to have it re-built if it acts up.

 

[dave1251]

200K miles on 2 trucks used for work. Sorry guys who say lack maintenance did them in. I disagree at any point both of the transmissions could have gone and really did not owe the owner a thing. How many hours are on the trucks?

 

[4WD]

Here is my ‘17 6L80e mag at 31k (added plug)

 

[Gasbuggy]

I will also say too long of an interval. I changed at 40k in my 6l90 car.

 

[Newman88]

These trucks are used as construction trucks, unfortunately I'm am the owner and mechanic/maintenance guy lol. I know chew me up guys.

But yes what got to me is that both failed close to the same mileage, while the Older GM's with alot more miles still going strong as well as the Fords and Rams with the same interval? Are these trucks more sensitive to fluid change? if so im blowing my brains out for not following the manufactures interval lolol.. Sorry guys thats what I get for not reading.

What's crazy is that both have the exact same symptoms thats why I mentioned if the 6l90 has "known" problems.

 

[Newman88]

Originally Posted by dave1251
200K miles on 2 trucks used for work. Sorry guys who say lack maintenance did them in. I disagree at any point both of the transmissions could have gone and really did not owe the owner a thing. How many hours are on the trucks?


I've got check the hours not sure how many, They probably have a minimum of 4k hours, they do idle alot.

 

[Newman88]

Originally Posted by spasm3
PM member clinebarger .


Why? Did he have a problem as well or is he going to chew me on the maintenance lol..

 

[Newman88]

No no, Im not swaping in no 4l80 I'm getting two rebuilt units just posted it because of what read I made the asumption the 6l90 was a faulty transmission.

 

[Newman88]

Originally Posted by ls1mike
The beauty is they have a drain plug and the pan is easy to drop.

If you drain the pan you get about 6.5 quarts out. The complete 6L90E system holds 12.4 quarts.
You can do a pan drop and filter swap every 10,000 miles and never have dirty fluid.
Easy Peasy.

I hate to say it, you murdered them.


No they don't have a drain plug, well on both my trucks. What would adding a drain plug be good for? I do complete drains including TC.

 

[cpayne5]

Originally Posted by Newman88
Originally Posted by spasm3
PM member clinebarger .


Why? Did he have a problem as well or is he going to chew me on the maintenance lol..


He's the resident transmission expert.

 

[dave1251]

Originally Posted by ls1mike
The beauty is they have a drain plug and the pan is easy to drop.

If you drain the pan you get about 6.5 quarts out. The complete 6L90E system holds 12.4 quarts.
You can do a pan drop and filter swap every 10,000 miles and never have dirty fluid.
Easy Peasy.

I hate to say it, you murdered them.


Mike I have to disagree there was no murder committed. 200K miles is a lifetime for any automatic transmission. Just because it's common for a transmission to go beyond this does not equal it's a expectation.

If a drain and fill is required during every oil change for any transmission this means GM makes dung and does not deserve anyone's business and should close up now.