My worktruck is a 2020 Silverado 2500 HD with the new 6.6L gasoline engine. In the summer of 2022, around 80,000 miles, I started to notice some grinding noise coming from the transmission under low revs and light acceleration. Finally, in November 2023, at 147,000 miles the transmission was diagnosed as slipping at 200 revolutions (in proportion to what I do not know) when the limit was supposed to be less 20 revolutions. The transmission was replaced a week later, and the problem resolved. The transmission received no service or maintenance its entire life.
Investigating which transmission this vehicle is equipped with, it seems to be either of the 6L80 or the 6L90, it seems the latter, but if someone else could add their evidence and come down solid on it, I would appreciate it.
This whole thing has irritated me significantly as all I ever got were arguments from my supervisor and the dealerships that the fluid doesn't need to be changed before 100,000 miles, and then when that number did come up, no one wanted to touch it for a fluid change. So I was left to do what I could to baby it along as I hate trashing stuff and rushing to the point where something has got to be replaced. I strategically made use of the manual gear limit/shifter on the steering column, and limited the engine to 5th when driving in the hills, and only let it into 6th when I made it out to the interstate. As well, I would start it in 2nd, and not let it shift into 3rd, and so on, until I could drop into the next gear at an engine RPM greater than 1700 RPM. My troubles seemed to be contained initially to all gears at engine RPMs in the range of 1400-1600. By 140,000 miles on the transmission, it had progressed to a range of about 1,000 RPM-2,000 RPM, and was starting to affect fuel economy, so I had it diagnosed and an estimate drawn up at my regular Chevrolet dealership for $99 during a regular oil change. As expected, my supervisor didn't trust it, but he had a big estimate in front of him, so I then had it rescheduled to be diagnosed at the Chevrolet dealership we bought the truck from in another city. The new diagnoses was the same, as was the price +/- tax rates I'm sure. So I got a new transmission, and I'm now allowed to have the transmission service at 30,000 mile intervals.
My ultimate question is whether regular fluid change and filter change on this transmission will really extend its life. I would like to hope so, and I may well have the truck long enough to find out, but I may be in a Ford Transit by next summer to make this all moot. What are others thoughts here?
Oh, and it seems to me that even when a GM transmission is serviced on time, that one should not expect it to last more than about 150,000 miles anyway. Does GM just not make quality transmissions to pair up with say the 3800?
Investigating which transmission this vehicle is equipped with, it seems to be either of the 6L80 or the 6L90, it seems the latter, but if someone else could add their evidence and come down solid on it, I would appreciate it.
This whole thing has irritated me significantly as all I ever got were arguments from my supervisor and the dealerships that the fluid doesn't need to be changed before 100,000 miles, and then when that number did come up, no one wanted to touch it for a fluid change. So I was left to do what I could to baby it along as I hate trashing stuff and rushing to the point where something has got to be replaced. I strategically made use of the manual gear limit/shifter on the steering column, and limited the engine to 5th when driving in the hills, and only let it into 6th when I made it out to the interstate. As well, I would start it in 2nd, and not let it shift into 3rd, and so on, until I could drop into the next gear at an engine RPM greater than 1700 RPM. My troubles seemed to be contained initially to all gears at engine RPMs in the range of 1400-1600. By 140,000 miles on the transmission, it had progressed to a range of about 1,000 RPM-2,000 RPM, and was starting to affect fuel economy, so I had it diagnosed and an estimate drawn up at my regular Chevrolet dealership for $99 during a regular oil change. As expected, my supervisor didn't trust it, but he had a big estimate in front of him, so I then had it rescheduled to be diagnosed at the Chevrolet dealership we bought the truck from in another city. The new diagnoses was the same, as was the price +/- tax rates I'm sure. So I got a new transmission, and I'm now allowed to have the transmission service at 30,000 mile intervals.
My ultimate question is whether regular fluid change and filter change on this transmission will really extend its life. I would like to hope so, and I may well have the truck long enough to find out, but I may be in a Ford Transit by next summer to make this all moot. What are others thoughts here?
Oh, and it seems to me that even when a GM transmission is serviced on time, that one should not expect it to last more than about 150,000 miles anyway. Does GM just not make quality transmissions to pair up with say the 3800?
