NHTSA opens preliminary probe into more than 870,000 GM vehicles

[jfoj]

This could get interesting and may give GM some wiggle room. We shall see what happens.

https://www.transportation.gov/sites/dot.gov/files/2025-01/Signed%20Secretarial%20Memo%20re%20Fixing%20the%20CAFE%20Program.pdf

 

[seatown]

This could get interesting and may give GM some wiggle room. We shall see what happens.

https://www.transportation.gov/sites/dot.gov/files/2025-01/Signed%20Secretarial%20Memo%20re%20Fixing%20the%20CAFE%20Program.pdf

Step in the right direction.
But what does it change for the current vehicles? GM can change oil recommendation? Release a standard warrantied AFM/DFM delete?

 

[jfoj]

Step in the right direction.
But what does it change for the current vehicles? GM can change oil recommendation? Release a standard warrantied AFM/DFM delete?

It may loosen up what GM and other manufacturers could do with making minor changes in ECM programming, part or featue disabling something like configuring the Auto Stop/Start to remember the last setting when the engine is shut off. Remomber during the "Chip Shortage" I think some of these trucks did not have the modules to operate the Auto Stop/Start and possibly the DFM system!

But if anything they changed signifigantly impacted the EPA rated Fuel Economy some folks might have a problem. I think most of us here would take a 1-2 MPG hit if it meant the engine could last 200,000+ miles without lifter, camshaft and bearing failures.

I am pretty well convinced these current failures are mostly due to oil that was speced, oil being fuel diluted, oil being run low due to fuel dilution causing high oil consumption, and the Auto Stop/Start feature and I do not have a lot of confidence in the 2 stage oil pump that is still being used on the 6.2l, the L84 5.3l did away with the 2 stage pump, they both have the same base variable displacement vane pump, just the 6.2l still has the 2 stage solenoid. Given the 6.2l operates consistently under High Torque Loading/Low RPM even while cruising on the highway. I would hate to see what happens when these trucks are loaded and/or towing. So a oil vicosity change could be on the horizon?? This could be addressed with electronic communicaitons, some paper and almost no cost to GM. BUT this will not solve any damage that has partially been done to existing engines.

 

[seatown]

I think most of us here would take a 1-2 MPG hit if it meant the engine could last 200,000+ miles without lifter, camshaft and bearing failures.

100% we would…
I was at the dealership yesterday and the only used they had was 4 ‘21 5.3L’s.
I asked about what they could do for disabling DFM. They came back with GM designed it this way.
So maybe something like this would change GM…?
Unfortunately that’s not going to happen tomorrow.

 

[jfoj]

Sad part is even disabling the AFM/DFM you still have all the junk in the engine. So it may reduce the probability of a failure, but still too many fragile things to fail over time. I am not sure I like the plastic lifter guides either? The lifter problem has likely been overshadowed by engine failures! The engines do not last long enough for the lifters/camshafts to fail!!!!

Again, oil and oil quality, oil cleanliness and proper oil level has a lot to do with how long the roller bearings in the lifters last, not to forget about the crazy lifter lockout system. Oil pressure may play into the bearing issues as well since there is no oil pressure measurement or sensor at the front main bearing oil supply. Oil/lack of, has something to do with all the bearing problems as well with a likely possibility of Low Speed Pre Ignition (LSPI) with the low RPM loads these engines operate under.

The proper way to solve the problem is address the oiling (viscosity and oil pump system), get all the AFM/DFM crap out of the engine and set the Auto Star/Stop to ALWAYs default to OFF then the engine is started, or program the feature out. But setting it to Default to Off at engine start allows people to use it if they see fit. You did not really loose a feature at that point.

Maybe the MID year 2025 6.2l will have an upgrade?

 

[seatown]

Question: Does the heavier oil loosen stuff up faster?
I know you noted they only recommend 0W20 cause of CAFE, but nothing to do with of all these fine moving pieces, tighter tolerances, higher pressures, etc?

 

[jfoj]

Not sure there are any tigher tolerances, just look at the "Lifter Bore" problem. These engines are not far from the 6.0l from 20 years ago, just with a bunch of crap hung on them. Some of the crap does wonders, well we know about the rest

Really an issue of bearing surface pressures and also oil retension when the engine is turned off. Higher viscosity oil will not "squeeze" as much as a lower viscostity oil, there is a lot of crazy physics, but the best way I can maybe describe it is higher viscosity oil has a higher surface tension (might not be the best way, but may help visualize a bit).

The other BIG problem is with fuel dilution of the engine oil. DI engines have a fair amount of fuel dilution issues by nature/design, I am sure Auto Stop/Start does not help, I am sure DFM may not help either. Remote starting to allow the engine to warn up at idle is also not good. As fuel dilutes the engine oil, the viscosity drops. So what you take out of the engine at an oil change is not what is going in as fresh oil.

So you start with a thin oil that may be bordeline for the application (Safety margins are good, not enough safety margin, well what can I say), then add fuel, once you add fuel, the oil consumption increases, if you have oil consumption and do not check the oil, the fuel concentration increases as the oil level drops, use the Remote Start feature too often (especially in the Winter and allow the engine to warm up 15 minutes, this is NO BUENO!!) the longer you wait between oil changes, the more fuel dilution. It is just a vicious cycle.

I have to do some testing, but the oil cooler may do great things, but it may also cause the oil to hold more fuel due to less "Cook Off". If the oil runs too cool, especially in the Winter months this could add to less fuel being "Cooked Off" during engine operation. Short trips in the Winter months are also a problem. Back many years ago, had an older lady making a lot of short trips in the Winter. The muffler became layered up with condesation until the engine would not start because the muffler was full of ice! I could just guess what the oil was like. Just an interesting example of what short trips in cold temps can cause.

Anyway, I do not expect to see any movement in the 6.2l for a solution for probably 6 months at the earliest unless the numbes are catastrophically high. A little mixing of the numbers and precentages and maybe they explain away the failures as trivial. Who knows, we may be having these same discussions years from now even with the 2025 6.2l??

I am not waiting on answers or solutions, I am doing what I can in my power to hopefully extend the life of my engine.

 

[seatown]

Not sure there are any tigher tolerances, just look at the "Lifter Bore" problem. These engines are not far from the 6.0l from 20 years ago, just with a bunch of crap hung on them. Some of the crap does wonders, well we know about the rest

Really an issue of bearing surface pressures and also oil retension when the engine is turned off. Higher viscosity oil will not "squeeze" as much as a lower viscostity oil, there is a lot of crazy physics, but the best way I can maybe describe it is higher viscosity oil has a higher surface tension (might not be the best way, but may help visualize a bit).

The other BIG problem is with fuel dilution of the engine oil. DI engines have a fair amount of fuel dilution issues by nature/design, I am sure Auto Stop/Start does not help, I am sure DFM may not help either. Remote starting to allow the engine to warn up at idle is also not good. As fuel dilutes the engine oil, the viscosity drops. So what you take out of the engine at an oil change is not what is going in as fresh oil.

So you start with a thin oil that may be bordeline for the application (Safety margins are good, not enough safety margin, well what can I say), then add fuel, once you add fuel, the oil consumption increases, if you have oil consumption and do not check the oil, the fuel concentration increases as the oil level drops, use the Remote Start feature too often (especially in the Winter and allow the engine to warm up 15 minutes, this is NO BUENO!!) the longer you wait between oil changes, the more fuel dilution. It is just a vicious cycle.

I have to do some testing, but the oil cooler may do great things, but it may also cause the oil to hold more fuel due to less "Cook Off". If the oil runs too cool, especially in the Winter months this could add to less fuel being "Cooked Off" during engine operation. Short trips in the Winter months are also a problem. Back many years ago, had an older lady making a lot of short trips in the Winter. The muffler became layered up with condesation until the engine would not start because the muffler was full of ice! I could just guess what the oil was like. Just an interesting example of what short trips in cold temps can cause.

Anyway, I do not expect to see any movement in the 6.2l for a solution for probably 6 months at the earliest unless the numbes are catastrophically high. A little mixing of the numbers and precentages and maybe they explain away the failures as trivial. Who knows, we may be having these same discussions years from now even with the 2025 6.2l??

I am not waiting on answers or solutions, I am doing what I can in my power to hopefully extend the life of my engine.

How do you record your more advanced data, such as live pressure?
I have just the basic odb2. But I am interested in compiling more data even for my 08. But especially for the new rig when I get it. Still haven’t decided what to get.

 

[jfoj]

So there are a few tools out there.

I am using a midrange Autel unit for some of the initial data, but I do not Log or capture date with this tool, you can graph on the display, however, I have not dug deep to see if the Autel can actually Log data. Graphing on the display is so, so, especially when you need to be driving!

OBDFusion Logs well, but does not have any Extended GM PID support. It is available for both Android and iOS, $10 tops for iOS, I think around $5 for Android. Only supports standard OBDII PID's but does have some in App purchase for other models, just no GM because of GM's licensing costs and once you stop paying for the licensing you have to remove Extended GM PID support. Developer just does not have the market to invest in GM support. I have met with him and worked with him over the years so I know what he is up against.

Torque Pro is $4.95 but for Android only. Torque Pro can pull in some GM extended PID's from the App with no additional cost. I have used both of these OBDFusion and Torque Pro for over 15 years. I just pulled in the Extended GM PID's on Torque Pro and at first glance it looks like it supports things like Oil Pressure, Oil Temp, Gear Position, Knock Sensor, Trans Temp, Torque Converter Slipage and some other useful PID's. I still need to confirm they are all properly supported on my 2024 Yukon. I never claim a win until I have really shaken everything down.

You will need a Bluetooth interface, expect to spend at least $25-$40, do not go too cheap as you may have some problems. A few challenges if you use the same phone that is tied to the Infotainment system, there may be some conflicts, you may need to delete the device from the truck for stability while Logging or use a different device.

I hope to gather some decent highway incline cruising this week if I have time. Need time and I need traffic to cooperate! Hope most of the Torque Extended PID's work properly as this will allow me to see more in detail about how the engine is loaded, which is rather heavily based on what I was initially seeing.

Message me if you want more details.

 

[KMeloney]

Can you tell me more about why you think it’s bad to remote start the truck and let it warm up? I don’t understand that at all. Thanks.

 

[jfoj]

Extreme fuel dilution in the engine oil. Best to start the engine, and drive withing 30 seconds or so depending on the ambient temperature. Clearly a bigger problem in the Winter when the temps are cold.

Some may choose to remote start the engine and allow it to warm up in the Winter for 15 minutes or so before getting in the vehicle. This is bad because the engine and engine oil actually take longer to warm up when not under a load.

The same can also occur in the Summer to allow the cabin to cool down, however, not at big of a problem compared to during the Winter.

Overall fuel contaminated engine oil can cause accelerated engine wear, quicker oil break down, increased oil consumption and set up the conditions for Low Speed Pre Ignition (LSPI). All things that can reduce the overall engine life and even in some cases cause catastrophic engine damage.

This testing was performed on a Diesel engine, but overall it is not much different than with a gasoline engine -

A few other useful videos that explain in more detail

 

[Scarey]

Good stuff, thanks.

 

[Vladimir2306]

Extreme fuel dilution in the engine oil. Best to start the engine, and drive withing 30 seconds or so depending on the ambient temperature. Clearly a bigger problem in the Winter when the temps are cold.

Some may choose to remote start the engine and allow it to warm up in the Winter for 15 minutes or so before getting in the vehicle. This is bad because the engine and engine oil actually take longer to warm up when not under a load.

The same can also occur in the Summer to allow the cabin to cool down, however, not at big of a problem compared to during the Winter.

Overall fuel contaminated engine oil can cause accelerated engine wear, quicker oil break down, increased oil consumption and set up the conditions for Low Speed Pre Ignition (LSPI). All things that can reduce the overall engine life and even in some cases cause catastrophic engine damage.

This testing was performed on a Diesel engine, but overall it is not much different than with a gasoline engine -

A few other useful videos that explain in more detail

It's all in one place here. Fuel getting into the engine oil has nothing to do with engine warming up. Warming up the engine is just necessary, and even on a hot day in the summer, you cannot start the engine and drive right away. Even in summer you need to let the engine warm up. It is the information that it is impossible to warm up as it is disseminated by environmentalists. In addition to the Yukon, I also have a BRP 300 horsepower jet ski, since no one cares about the environment, and it requires warming up for at least 2-3 minutes at idle, and then 5-10 minutes at medium speed. This is provided that the jet ski is used in hot weather.
So, warming up the engine, especially in winter, is necessary; remote start is great for this, which makes warming up faster, keeping the speed higher. Next, does fuel get in during warm-up or when idling? Yes, it does.
Fuel gets into the oil when the car moves around the city at low speeds. To burn it out of the oil, you need to regularly drive at high speeds of 2500-3500 crankshaft revolutions per minute. At this moment, the engine, oil and fuel in it become very hot, and the fuel evaporates. Therefore, cars that drive fast on the highway do not have the problem of fuel in the oil.
To summarize, if you don’t warm up the engine and drive straight away, this will not get rid of the problem of fuel in the oil, because fuel gets there from driving slowly. But an engine without warming up can get much more problems due to uneven heating, getting scuffed inside.
I already wrote above that the problem with GM engines is not oil. The previous generation also runs great on 0-20 oil. And I myself have driven 0-20 oil in the 2022 Yukon for 115 thousand km. The problem is poor quality engine assembly. Something went wrong at GM; new engines come out of the box with seized pistons. Bearings are a consequence, not a cause.

 

[seatown]

It's all in one place here. Fuel getting into the engine oil has nothing to do with engine warming up. Warming up the engine is just necessary, and even on a hot day in the summer, you cannot start the engine and drive right away. Even in summer you need to let the engine warm up. It is the information that it is impossible to warm up as it is disseminated by environmentalists. In addition to the Yukon, I also have a BRP 300 horsepower jet ski, since no one cares about the environment, and it requires warming up for at least 2-3 minutes at idle, and then 5-10 minutes at medium speed. This is provided that the jet ski is used in hot weather.
So, warming up the engine, especially in winter, is necessary; remote start is great for this, which makes warming up faster, keeping the speed higher. Next, does fuel get in during warm-up or when idling? Yes, it does.
Fuel gets into the oil when the car moves around the city at low speeds. To burn it out of the oil, you need to regularly drive at high speeds of 2500-3500 crankshaft revolutions per minute. At this moment, the engine, oil and fuel in it become very hot, and the fuel evaporates. Therefore, cars that drive fast on the highway do not have the problem of fuel in the oil.
To summarize, if you don’t warm up the engine and drive straight away, this will not get rid of the problem of fuel in the oil, because fuel gets there from driving slowly. But an engine without warming up can get much more problems due to uneven heating, getting scuffed inside.
I already wrote above that the problem with GM engines is not oil. The previous generation also runs great on 0-20 oil. And I myself have driven 0-20 oil in the 2022 Yukon for 115 thousand km. The problem is poor quality engine assembly. Something went wrong at GM; new engines come out of the box with seized pistons. Bearings are a consequence, not a cause.

You had an update of pictures?

 

[jfoj]

It's all in one place here. Fuel getting into the engine oil has nothing to do with engine warming up. Warming up the engine is just necessary, and even on a hot day in the summer, you cannot start the engine and drive right away. Even in summer you need to let the engine warm up. It is the information that it is impossible to warm up as it is disseminated by environmentalists. In addition to the Yukon, I also have a BRP 300 horsepower jet ski, since no one cares about the environment, and it requires warming up for at least 2-3 minutes at idle, and then 5-10 minutes at medium speed. This is provided that the jet ski is used in hot weather.
So, warming up the engine, especially in winter, is necessary; remote start is great for this, which makes warming up faster, keeping the speed higher. Next, does fuel get in during warm-up or when idling? Yes, it does.
Fuel gets into the oil when the car moves around the city at low speeds. To burn it out of the oil, you need to regularly drive at high speeds of 2500-3500 crankshaft revolutions per minute. At this moment, the engine, oil and fuel in it become very hot, and the fuel evaporates. Therefore, cars that drive fast on the highway do not

Fuel gets into the oil when the car moves around the city at low speeds. To burn it out of the oil, you need to regularly drive at high speeds of 2500-3500 crankshaft revolutions per minute. At this moment, the engine, oil and fuel in it become very hot, and the fuel evaporates. Therefore, cars that drive fast on the highway do not have the problem of fuel in the oil.

Vladimir,

I have a few questions:

1. How regularly/often do you drive at high speed with the engine RPM between 2500-3500?

2. How far (distance)/long (time) do you typically drive at high speed with the engine RPM between 2500-3500?

3. How fast do you typically drive at high speed with the engine RPM betwen 2500-3500?

4. What transmission setting do you typically drive at high speed with the engine RPM between 2500-3500?

5. Have you performed any oil analysis of your engine oil at time of oil changes?

 

[Vladimir2306]

You had an update of pictures?

No, there are no new photos))) they appear in our chat periodically

 

[Vladimir2306]

Vladimir,

I have a few questions:

1. How regularly/often do you drive at high speed with the engine RPM between 2500-3500?

2. How far (distance)/long (time) do you typically drive at high speed with the engine RPM between 2500-3500?

3. How fast do you typically drive at high speed with the engine RPM betwen 2500-3500?

4. What transmission setting do you typically drive at high speed with the engine RPM between 2500-3500?

5. Have you performed any oil analysis of your engine oil at time of oil changes?

If we are talking about the track, then I drive fast and a lot. for example, a month ago I drove from one city to another at a distance of 660 km, with an average speed of 141 km/h, this turns out to be 412.5 miles, with a speed of 88 miles per hour. I drove almost the entire way on cruise control at a speed of 170 kmh (106 mph) and in this mode the revolutions were about 3500 per minute. It was over 4.5 hours continuously.
No, I didn’t do an oil analysis, I don’t see any point in it.
It’s enough for me that when I change the oil (and I change it every 12,000 km (7,500 miles)) they cut open the oil filter and examine what’s inside.
I drive on the highway in Normal mode. If with a trailer, then in Trailer mode.
I usually travel long distances once a month on average. Or approximately every 3-5 thousand kilometers.
If we are talking about everyday driving. So yes, I always warm up the engine. Both in winter and in summer.
In the summer, I start the engine from the key fob, and while I’m leaving the car it works for 2-3 minutes. If in winter, then I start it at least 10-15 minutes before leaving the house, so that the car is completely warmed up and the interior is warmed up. In winter we have frosts down to -25-35C.
Then for the first few distances I drive calmly, without increasing the engine speed much, until the car warms up completely.
And then, in the city, sometimes I can put the gas pedal to the floor. To periodically bring the speed up to the red zone. This burns fuel out of the oil perfectly) and, in principle, I really like the feel of the V8 during acceleration.

 

[Antonm]

The whole warm-up thing has little to do with fuel dilution its more about coolant temperature and the resultant increase in ring wear from running a cold engine.

So the people above have the right answer, just the wrong reason. Engine wear and coolant temperature are inversely proportional (within the normal ranges of coolant temperature anyway) and the longer you spend with cold coolant, the worse it is .

Pretty much the breaking point is 160F or 71C coolant temp, below that you get more significantly more engine wear. So you want to minimize the time the engine is running with coolant temp below 160F /71C.

Fast forward the below video to about the 29 minute mark and start watching from there (or watch the whole thing, its decently entertaining), he does a pretty good of explaining and showing the documents from real engineers (not random internet guessers/ influencers/ personalities,,, real engineers) about what's actually happening and why warming up by idling is unnecessary and actually slightly detrimental to engine service life.

...

 

[Jay P Wy]

Interesting video.

1.2M views · 19K reactions | It Blew up at 4 Miles! Part failure or assembly error? GMC 6.2L #enginebuilding #EngineRepair #autoshop #autorepair | Dave's Engines

It Blew up at 4 Miles! Part failure or assembly error? GMC 6.2L #enginebuilding #EngineRepair #autoshop #autorepair

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[jfoj]

The 4 mile failure may have already been included here in this thread earlier. That was not a bearing issue, the piston pin retaining clip was either not properley seated, missing or the piston pin retaining clip groove was not machined. The problem is the engine was already opened up before the guy in the YouTube video received it.

Sad ending for a nice engine.