Is my transmission in danger?

[john1]

I recently bought a great used 2007 Silverado 5.3 2wd with only 78k miles. 
I seen the carfax that the trans fluid was changed at 15k. So I decided to flush the system. But now I’m nervous that it might’ve been a bad decision and I might have done more damage in the long run. The flush didn’t include a new filter either so I might have it changed. Anyone think it’s going to deteriorate sooner or later? 

Edited December 4, 2020 by john1
Typo

[Brian715]

I think in my experience these transmissions are not going to make it forever anyway. I've had them fail around 150,000 and I've had them go to 250,000 before needing replaced. If it goes out tomorrow, I don't think it really owes you anything. And yes I have heard that flushing a trans that's never had a flush can do more harm than good but never experienced that. It was our policy at the shop not to flush anything over 150,000 miles if they couldn't prove it had been flushed at regular intervals already. I would change the filter and start preparing for a trans rebuild in the future. 

[Jsdirt]

To the OP:

 

I've owned the same truck since new (if you're talking about the GMT-900, and not the 800 classic), and my transmission just lost 3rd and 4th at 103k miles. The clock is ticking, so I wouldn't worry too much about it.

[john1]

On 12/4/2020 at 7:32 AM, Brian715 said:

I think in my experience these transmissions are not going to make it forever anyway. I've had them fail around 150,000 and I've had them go to 250,000 before needing replaced. If it goes out tomorrow, I don't think it really owes you anything. And yes I have heard that flushing a trans that's never had a flush can do more harm than good but never experienced that. It was our policy at the shop not to flush anything over 150,000 miles if they couldn't prove it had been flushed at regular intervals already. I would change the filter and start preparing for a trans rebuild in the future. 

Thanks for the insight man. I think that that is a great policy just for the fact that you’re putting profits after customers well-being. 
I changed the filter and to my surprise the magnet had normal amount of metal and the pan had barley any discoloration. 
Hope it lasts!

[john1]

On 12/13/2020 at 2:58 PM, Jsdirt said:

To the OP:

 

I've owned the same truck since new (if you're talking about the GMT-900, and not the 800 classic), and my transmission just lost 3rd and 4th at 103k miles. The clock is ticking, so I wouldn't worry too much about it.

Yep GMT-900. Dang did you get it rebuilt or just buy a new one? 
 How was your driving style mostly like? And do you live in a rough temperature climate? 

[Jsdirt]

My foot is frequently to the floor, and I did tow cars alot with my flatbed trailer (2k lb. empty weight), but only twice had the trans. temp over 200° briefly on 90°+ summer days on a long, steep hill with my foot in it more than it should've been. Live in MA, so I've seen lows of -16°F in winter, and highs of 95°F & 65% humidity in summer. Lots of hills, lots of traffic towards the eastern part of the state. That said, this truck never got abused like my older stuff - back in those days I was ALWAYS racing around, slamming gears, towing stupid heavy loads, and never changed transmission fluid or gear oil, ever. Only had 2 transmission failures in all my years of driving before this, and each had well over 250k miles on them. I'd wager over 300k based on the overall condition of the vehicles. At 40k miles with the Silverado, both my rear diff and transmission got flushed and filled with Signature Series Amsoil synthetics. I replaced my differential after finding all the tips of my spider gears in the magnet on the rear cover in spring of 2019. Who knows how long it had been this way. Had 97k on it when I installed a pneumatically controlled OX Locker. I ran the heavier 75w-110 weight Severe Gear for extra protection, too. Clutches in the G80 were GONE, too. Backlash was .011", and the diff carrier itself was all worn out and sloppy - the slop in the spider pin was scary. Amazed it held together as long as it did  ...

 

I bought a brand new, built-to-the-moon Heavy Hauler transmission from PerformaBuilt. Very happy with it so far. They take all of GM's poor engineering and cheap parts, and re-engineer it into something bulletproof. My new trans has 5-pinion planets, the best clutches with WIDE bands, hydraulic mods to the valve body, oiling mods in a few key areas, The Beast sunshell, and Sonnax Smart Tech drum, among other things. Finished it off with a FTI 2,000 RPM stall converter. This transmission will handle over 500 rear-wheel horsepower. It cost a pile of money, but now I can tow over my weight capacity with my foot to the rug, theoretically, and it will not break.

 

My engine and transfer case are next to fail. 103k miles - place your bets now! 

 

EDIT just to add, fluid int his transmission was always bright red, like the day it got dropped off from the dealership in spring of '07. There was no warning for my failure, either. One minute it was working, the next, it hit neutral after 2nd gear. 3rd and 4th ceased to exist, like a light switch. The pan was all clutch material when I dropped the fluid for removal.

Edited December 15, 2020 by Jsdirt
Added key info