LT6 engine failures/problems
Drifting
Joined: Jan 2023
Posts: 1,758
Likes: 1,494
2024 C8 of the Year Winner - Unmodified
And it seems my issues aren't over even after my engine replacement. Driven a little over 400 miles on the new engine and it started to sound a little off and feel sluggish. Engine note became less singing and more growling, no MIL or vibrations. When I get home, I decide to check the oil level, which I had not yet done since the replacement (yes, I know, should have checked at the dealer before I drove off. Hindsight 20/20, etc.). Following the procedure in the manual (coolant temp at 175F, engine idling), I just about had a heart attack. According to the dip stick, the oil level is a foot or more above the full mark. There was oil all the way to just a couple inches below the cap. I wiped the stick and rechecked about 3 more times, just to make sure I wasn't going crazy, and it was the same extremely high reading each time. And after letting the car cool and sit overnight, I checked without starting the car to confirm my suspicions: the oil level reads at the normal level, when off...
I'm furious right now, the car has gone through most of its break-in period with what must be almost double the correct amount of oil. I have no idea what possible wear or damage has been done. My dealer will be hearing from me later this morning, and I am not going to let them off the hook for this. All of my care following the engine break-in to the letter ruined by their complete incompetence.
Is there any chance that the engine has not been damaged or prematurely worn? I never saw smoke during the time I drove it, but something was definitely not right the last ~15 miles.
I'm furious right now, the car has gone through most of its break-in period with what must be almost double the correct amount of oil. I have no idea what possible wear or damage has been done. My dealer will be hearing from me later this morning, and I am not going to let them off the hook for this. All of my care following the engine break-in to the letter ruined by their complete incompetence.
Is there any chance that the engine has not been damaged or prematurely worn? I never saw smoke during the time I drove it, but something was definitely not right the last ~15 miles.
But if it was that drastically overfilled, oil likely got into the vent line in the tank that goes to the intake. Oil may be all over the intake and maybe valves.
Heel & Toe
Joined: Oct 2020
Posts: 19
Likes: 35
From: Georgetown, TX
Could it have gotten oil on the MAF sensor and caused the ECU to pull timing?
Drifting
Joined: Jan 2023
Posts: 1,758
Likes: 1,494
2024 C8 of the Year Winner - Unmodified
Advanced
Joined: Jul 2019
Posts: 50
Likes: 10
From: columbus ms
I am here. I have been messed up since the soy bi products attracted rats in my car and cause havoc on the washer fluid bottle, wiring for PDR. air ducts and now my Service advisor say the harness for the body control has had some damage. now if GM is using this soy product in the vehicles it should be known so customers can take precautions measure to keep, they butt out of a 110k car. I see that Honda and Toyota has lawsuits in, on that same problem. now i have 7000 dollars worth of damage to my car WTH!!!
Burning Brakes
Joined: Mar 2013
Posts: 814
Likes: 93
From: South Lousiana (Cajun Boys with Bad ASS Toys)
I am here. I have been messed up since the soy bi products attracted rats in my car and cause havoc on the washer fluid bottle, wiring for PDR. air ducts and now my Service advisor say the harness for the body control has had some damage. now if GM is using this soy product in the vehicles it should be known so customers can take precautions measure to keep, they butt out of a 110k car. I see that Honda and Toyota has lawsuits in, on that same problem. now i have 7000 dollars worth of damage to my car WTH!!!
Instructor
Joined: Jul 2014
Posts: 108
Likes: 57
From: Jacksonville Beach Fla
Just a thought.
As a prior owner of Gen 1 and Gen 2 GT350 FPC's that both never had any issues and didn't use a drop of oil. The 350 like the Z06 it has huge oil coolers. When I lived in a cooler climate driving at anything less than 60 degrees the engine oil took forever to get to operating temp. Sometimes driving to work 15 miles didn't come close. So I NEVER ran the RPM's above 3K. As we know these FPC engines spin up quick and put a ton of stress on the engine when cold. Not saying those with LT6 engine issues didn't watch the oil temp prior to running high rpm's. Or that's the reason for issues,
Just getting my Z06 a few weeks ago yesterday took her out for a spin. I noticed my oil temps took quite a while to rise to normal and it was 75 out.
As a prior owner of Gen 1 and Gen 2 GT350 FPC's that both never had any issues and didn't use a drop of oil. The 350 like the Z06 it has huge oil coolers. When I lived in a cooler climate driving at anything less than 60 degrees the engine oil took forever to get to operating temp. Sometimes driving to work 15 miles didn't come close. So I NEVER ran the RPM's above 3K. As we know these FPC engines spin up quick and put a ton of stress on the engine when cold. Not saying those with LT6 engine issues didn't watch the oil temp prior to running high rpm's. Or that's the reason for issues,
Just getting my Z06 a few weeks ago yesterday took her out for a spin. I noticed my oil temps took quite a while to rise to normal and it was 75 out.
New Member
Joined: May 2026
Posts: 8
Likes: 3
GT350 of 2026
They are most likely going to come up with .2 for the engine; if you remember, GT350s were breaking down left and right due to it being a flat V8, and if you push your memory far back, 458's had the same issues; they would go up in flames. These are race engines, they don't last that long, that's why Ferrari left V8s and and v12s are cross. But yeah, no solution.
Well, at least we know they copied 458 well lol... and I have heard they are going to copy McLaren for C9
Well, at least we know they copied 458 well lol... and I have heard they are going to copy McLaren for C9
Instructor
Joined: Nov 2022
Posts: 106
Likes: 96
They are most likely going to come up with .2 for the engine; if you remember, GT350s were breaking down left and right due to it being a flat V8, and if you push your memory far back, 458's had the same issues; they would go up in flames. These are race engines, they don't last that long, that's why Ferrari left V8s and and v12s are cross. But yeah, no solution.
Well, at least we know they copied 458 well lol... and I have heard they are going to copy McLaren for C9
Well, at least we know they copied 458 well lol... and I have heard they are going to copy McLaren for C9
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Advanced
Joined: Mar 2015
Posts: 73
Likes: 22
From: North NJ
I just finished my break in period today, it was so tough keeping it under 4k rpm!!!
The tach redline changed while I was driving about a half mile after I hit 500, I found the space/time to nail it to redline through at least 2-3 gears about 10 times after and it was spectacular!!! No problems here at all it's insanely awesome!
The tach redline changed while I was driving about a half mile after I hit 500, I found the space/time to nail it to redline through at least 2-3 gears about 10 times after and it was spectacular!!! No problems here at all it's insanely awesome!
Racer
Joined: Apr 2025
Posts: 266
Likes: 219
From: Long Island New York
I just finished my break in period today, it was so tough keeping it under 4k rpm!!!
The tach redline changed while I was driving about a half mile after I hit 500, I found the space/time to nail it to redline through at least 2-3 gears about 10 times after and it was spectacular!!! No problems here at all it's insanely awesome!
The tach redline changed while I was driving about a half mile after I hit 500, I found the space/time to nail it to redline through at least 2-3 gears about 10 times after and it was spectacular!!! No problems here at all it's insanely awesome!