LT6 engine failures/problems
Pro
Joined: Jan 2020
Posts: 562
Likes: 521
You're off-base with the recommendation/interpretations and blaming this all on "abuse". People are having leaking transmissions at PDI or after only a few hundred miles of use. There are case porosity issues (bad castings) and various gasket and seal issues. If GM wanted to break-in to be differently they would have stated as such. The engine is broken in at assembly and first run-in. The other guidelines (500 and 1,500) are for the DCT gears to develop sufficient wear-patterns for a long service-life. The first 500 miles they suggest a lower redline and torque management is active. No launches, no hard use etc. From 500-1,500 you can launch and use the car, but no trackday use i.e. extended high heat or extended loading of the car.
The main issue sets with these cars so far are:
1. Engine vale lash (the tick)
2. Trans leaks (porosity, parts defects)
3. Trans debris causing premature valve-body failure (assembly debris, poor valvebody design)
One member is on his 4th valvebody and was told they recently redesigned it.
GM is adamant that the break-in is 7,500 and if you do the trans filter early, you MUST do it again at 7,500 to have warranty. On all 3 of my Stingrays I do the first oil change and trans filter at 2,000 miles and then again within 7,500 more. This was all before GM clarified the "YOU MUST DO IT AT 7,500 NO MATTER WHAT" update.
For my Z06 I will do oil and trans filter when I get it home from the NCM (about 1,200 miles) and then again at 7,500.
The main issue sets with these cars so far are:
1. Engine vale lash (the tick)
2. Trans leaks (porosity, parts defects)
3. Trans debris causing premature valve-body failure (assembly debris, poor valvebody design)
One member is on his 4th valvebody and was told they recently redesigned it.
GM is adamant that the break-in is 7,500 and if you do the trans filter early, you MUST do it again at 7,500 to have warranty. On all 3 of my Stingrays I do the first oil change and trans filter at 2,000 miles and then again within 7,500 more. This was all before GM clarified the "YOU MUST DO IT AT 7,500 NO MATTER WHAT" update.
For my Z06 I will do oil and trans filter when I get it home from the NCM (about 1,200 miles) and then again at 7,500.
Last edited by C8Zeb06; Aug 23, 2023 at 09:01 AM.
Melting Slicks
Joined: Aug 2000
Posts: 3,430
Likes: 972
From: Overland Park KS
This Tremec designed DCT may well end up costing GM a great deal in after sale warranty claims. One wonders how long before the NHTSA takes a look at it, and whether GM might have to end up with a stop sale on the car like Porsche had to do with the 2014 GT3s.
I sincerely hope not, and as many have stated before, the number of 'faults' are always amplified on forums. But I for one would be glad to be able to get a second or perhaps third model year car at this rate.
I sincerely hope not, and as many have stated before, the number of 'faults' are always amplified on forums. But I for one would be glad to be able to get a second or perhaps third model year car at this rate.
Melting Slicks
Joined: Oct 2004
Posts: 2,187
Likes: 173
From: Nevada
This guy got lots of metal shavings in his oil for his 1st oil change, is it normal?
I will have dealer change my 1st oil change at around 2500 miles since I don't do it myself, should I ask to look at the used oil and have them save some oil so I can send to lab? Or there is no need unless there is ticking noise and other problems?
I will have dealer change my 1st oil change at around 2500 miles since I don't do it myself, should I ask to look at the used oil and have them save some oil so I can send to lab? Or there is no need unless there is ticking noise and other problems?
Instructor
Joined: Mar 2001
Posts: 179
Likes: 17
From: Dallas (area) Texas
FYI - on each DCT external filter change, whether part of regular maintenance or with a repair that still requires the external filter to be changed due to possible debris, there is a flush procedure through the dealer scan tool (MDI2). I don't know if any other aftermarket scan tool has access to the flush procedure. Of course, a fresh filter change without the flush procedure is better than a dirty filter.
This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.
The following will occur when the scan tool control is enabled: Engine Speed = 2,000 RPM & Line Pressure = Increase — For 8 min
This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.
The following will occur when the scan tool control is enabled: Engine Speed = 2,000 RPM & Line Pressure = Increase — For 8 min
Pro
Joined: Jul 2023
Posts: 607
Likes: 559
FYI - on each DCT external filter change, whether part of regular maintenance or with a repair that still requires the external filter to be changed due to possible debris, there is a flush procedure through the dealer scan tool (MDI2). I don't know if any other aftermarket scan tool has access to the flush procedure. Of course, a fresh filter change without the flush procedure is better than a dirty filter.
This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.
The following will occur when the scan tool control is enabled: Engine Speed = 2,000 RPM & Line Pressure = Increase — For 8 min
This procedure is used to flush the transmission fluid through the filtration system before a repair is performed that may have been caused by debris in the fluid.
The following will occur when the scan tool control is enabled: Engine Speed = 2,000 RPM & Line Pressure = Increase — For 8 min
Burning Brakes
Joined: Nov 2021
Posts: 1,198
Likes: 1,009
From: TDot
This guy got lots of metal shavings in his oil for his 1st oil change, is it normal?
https://www.youtube.com/watch?v=Guju1K8XLwo
https://www.youtube.com/watch?v=S8vCrZo4d_k&t=5m22s
I will have dealer change my 1st oil change at around 2500 miles since I don't do it myself, should I ask to look at the used oil and have them save some oil so I can send to lab? Or there is no need unless there is ticking noise and other problems?
https://www.youtube.com/watch?v=Guju1K8XLwo
https://www.youtube.com/watch?v=S8vCrZo4d_k&t=5m22s
I will have dealer change my 1st oil change at around 2500 miles since I don't do it myself, should I ask to look at the used oil and have them save some oil so I can send to lab? Or there is no need unless there is ticking noise and other problems?
Ask the techs to collect a sample and send it off. I'd ask the dealer to give you the old filter to cut open for piece of mind.
I've always changed the oil on new cars at 1000km (600 miles) and sent out the sample.
Race Director
Joined: Nov 2017
Posts: 12,759
Likes: 10,655
From: Prosper TX/Austin TX
2020 C6 of the Year Winner - Modified
At least with my Z06 I can buy a set of aftermarket heads and pretty much eliminate any potential issues with my LS7. C8 Z owners have no options for the DCT or LT6.
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Drifting
Joined: Jul 2006
Posts: 1,910
Likes: 2,693
Race Director
Joined: Nov 2017
Posts: 12,759
Likes: 10,655
From: Prosper TX/Austin TX
2020 C6 of the Year Winner - Modified
Pro
Joined: Jul 2023
Posts: 607
Likes: 559
Pro
Joined: Jul 2023
Posts: 607
Likes: 559
Racer
Joined: May 2021
Posts: 403
Likes: 64
@douglasjre Youtube, but don't give him the views/clicks. 
Last edited by douglasjre; Sep 19, 2023 at 12:31 AM.
Race Director
Joined: Nov 2017
Posts: 12,759
Likes: 10,655
From: Prosper TX/Austin TX
2020 C6 of the Year Winner - Modified
He doesn't actually say anything, except "ooh I figured it out, once I expose this, GM is going down..." he hasn't figured anything out nor does he have anything to expose. He's an idiot, plain and simple.
Racer
Joined: May 2021
Posts: 403
Likes: 64
Advanced
Joined: Oct 2008
Posts: 54
Likes: 21
From: Northampton MA
The engine is holding up, so far, and oil levels have remained steady. I haven't had to add a drop. I did a complete oil, DCT fluid and DCT filter change just before I hit 2,000 miles and after 2 track days.
The guy has stream of conscience complaints.....first it was the ELSD, then the carbon ceramic brakes, then the "tick", then the ABS, then gasoline in the oil. I don't know. Maybe we're the fools, not him. We'll see, I guess.