just for perspective, my buddy has 2014 gmc sierra (i believe denali but might be wrong), the one with v8 and cylinder deactivation. anyhow, just couple of weeks ago with 115k on the clock (no towing till 90k and just recently some towing), transmission took a dump out of the blue. He was told 3rd and 4th gear did something that destroyed everything internally. He also has been told that it's about how much you can get out of these transmissions. oh, and he had tranny fluid changed once at 90k or so.
out of the blue according to my friend. he's not a car guy by any stretch of the imagination and could care less about noises or symptoms his truck would produce trying to warn him. his other rig (land rover) went through new engine, turbo, differential and many other items. sooo, it is what it isOut of the blue? 6L80E converter clutch failure is VERY common on '14 & up 1500 pick-ups. They start acting up way before they just quit.
Maybe the oil usage is the valve cover issue that I had? I went from using about a qt in 2.5k miles and filling a catch can in one day…to 2.5k miles and the oil is 1/3 of the way down to the full and catch can is about 1/3 full. Watch for occasional smoke on startup is a dead giveaway of this problem. Valve seals are not an issue on these engines usually.An update on my yukon and escalade:
Yukon went through 1qt of oil in 1500 miles due to burn and some dripping from the pan. It has been giving us 17 mpg in 80 mph highway winter condition use. Nothings broken yet.
Escalade is not burning noticeable oil but its also only 112k vs 195k miles. Terrible economy at just under 10 short trip city use.
Both are fantastically comfortable and enjoyable to drive. Lumbar and heating on the escalade is nice and missing on the Yukon. No repairs needed here.
I gotta say buy one of these GMT 800 platforms if you get the chance at a clean example.
I will have to look into the valve cover thing. would be nice if thats all it is. I like easy LS fixes.Maybe the oil usage is the valve cover issue that I had? I went from using about a qt in 2.5k miles and filling a catch can in one day…to 2.5k miles and the oil is 1/3 of the way down to the full and catch can is about 1/3 full. Watch for occasional smoke on startup is a dead giveaway of this problem. Valve seals are not an issue on these engines usually.
It was probably the easiest repair I’ve done and the most satisfying considering the difference it made.I will have to look into the valve cover thing. would be nice if thats all it is. I like easy LS fixes.