Denalis stopping while driving- class action suit?

[jfoj]

Assume the replacement vehicle has a 6.2l?

So if you do not want this problem to occur again, I would suggest you do the following, which I am doing.

1. Run ONLY Premium fuel in the vehicle,

2. DO NOT use the remote start feature or start the engine to allow it to warm up, especially in the colder months, or in the Summer to cool off. Start the engine, allow the RPM to drop down (20-30 seconds), put the vehicle in gear and drive it.

3. DO NOT use the Auto Stop/Start feature. Suggest you get a Range DFM disabler, about $250, it disables the Auto Stop/Start feature and disables the DFM while under load. The other option to work around the DFM at least for most daily driving is put the transmission in L9 rather than D. This eliminates DFM around town up to about 50 MPH without much loss in fuel economy. But you will want to run the transmission in D for the highway, but the DFM would be active in D without a disable device.

4. DO NOT allow the OLM to go to 0%, change the oil at 50%, which is around every 3000 miles.

5. DO NOT use 0W20 engine oil, use 5W30 or 0W40. Especially if you tow or load the vehicle with more than a few passengers.

6. Run 9 quarts of oil with filter change in the engine, 8 quarts is not enough even though all the documention states this. These engines require at least 8.5 quarts, but 9.0 will not hurt the engine.

7. Check the oil level on the dipstick every 2nd fill up, the low light comes on at 2 quarts low.

I am sure there will be a LOT of comments, but I have been doing a lot of research on these failures and this is all you can do to counter any possible future failures. The biggest problems is 0W20 engine oil that becomes fuel diluted and not running Preminum fuel. Almost all of these engine failures have been oil related, a few have been due to piston wrist pin locking ring problems. Almost all of these engines have failed while cruising on the highway as well. Low oil, fuel contaminated oil seem to be a reoccuing theme.

Let the comments begin!

 

[KMeloney]

@jfoj — A not entirely rhetorical question: At this point [in the course of all of the failures], why wouldn’t GM make the same recommendations? (Never mind the auto stop and DFM overrides, as I’m sure they can’t recommend things that defeat their integrated systems.) They’ve already acknowledged (quietly) that they’ll replace seized engines, so I don’t see why recommending higher visc oil, or limiting warm up time, etc, would be detrimental for GM to embrace and promote — especially if it staves off engine failures and replacements.

Yes, a big part of me wonders if those recommendations are NOT beneficial. But I’m just trying to learn as much as I can about all of this, and don’t have enough knowledge to say who/what is right or wrong.

I certainly appreciate your continued search for the answers here.

 

[jfoj]

KMeloney, I appreciate your interest to learn and understand. We are and have been sold a bill of goods for a long time. Ever since GM moved away from the older 6.0l in the mid 2000's we have all been forced to SUFFER with AFM, 0W20 engine oil, Auto Stop/Start and all sorts of other foolishness and we are all paying premium money for stuff that is unreliable, breaks often and way too expensive and time consuming to repair. An we are all supposed to like this and smile about it! Even the 6.6l gasoline engines are having failures without the AFM, but they are DI and fuel dilution of the engine oil is a common denominator even with a higher viscosity oil spec for the 6.6l, but these engines are also probably pulling heavy loads on towing on a fairly regular basis.

GM cannot just disable, take off, or recommend the owners do things like turn off the Auto Stop/Start. Just turn off the Auto Stop/Start, the feature does not hold the setting when the engine is turned off, you have to turn it off EVERY time you start the engine. EPA, CAFE and governmental regulatons are all forcing the auto manufacturers to features/add ons like the Auto Stop/Start and DFM. In order for the manufacturers to try to increase fuel economy, they added the Auto Stop/Start and DFM system along with multispeed transmissions with multiple overdrive gears and moved to 0W20 engine oil. But even if GM indicated they should be disabled, we all paid extra for this garbage! None of these things were really added to increase reliability and longivity of the vehicle as this is not as much of a priority as fuel ecomony and checking some boxes that the government required.

Here is the real problem, todays DI gasoline engines while having a much higher power density than older port fuel injected engines really have problem with fuel dilution of the oil. Many 10-20 minute short trips are also likely to keep the oil from getting up to temperature as well. Keep in mind you may start out with 0W20 engine oil, but as fuel is mixed in this oil, the viscosity drops and with the high torque peaks on a regular basis, the fuel diluted oil is just not going to protect the engine. The only way to even start to cook out any fuel in the engine oil is the engine will need to be driven probably at least for 30 minutes at a minimum and more likely 45 minutes to 1 hour. If you tow with one of these trucks or load up a family of 3-6 passengers and all the associated gear, I would not want to rely on 0W20 oil at all.

GM and other manufacturers have provided high power keyfobs and Apps that allow you to remote start your engine and allow the engine to run for up to typically 15 minutes to warm up or cool off the cabin. Doing this is dangerous to any engine, but really bad and tough on DI engines. So if the manufucter tells you not to run the engine for 15 minutes before driving, then why did they give you all the remote start options? Sure you can walk out and start the car as well without the keyfob or App, but you are less likely to do this. I am surprised the government has not outlaw the remote start features due to additional fuel useage and emission output!!! Might be coming to a town near you in the futurer?

Every 10 years in the auto industy there appears to me major changes that impact how and engine is built, operates and runs as well as often some of the changes reduce the reliability and lifespan of the engines. Start back from 1960 and follow each decade and you will see all the changes, many have not been such great ideas. Then the marketing starts to extend mainteance and oil changes. Hell today you have oils that claim they can protect your engine for 25,000 miles and oil filters that claim they can last 20,000 miles. This is not happening on any of my vehicles, especially any of the DI gasoline engines. I am changing oil about every 3000 miles or when the OLM hits 50%.

The problem is nobody drives vehicles under ideal conditions and even if they do, I guarantee you 5-10 years from now everyone that is knowledgeable will say that running oil changes out to 10,000-25,000 miles was foolish! What most people do it put their engines through hell and do not even realize it. What you used to be able to do for your port fuel injected engines is really bad for a DI engine.

As far as Premium fuel, nothing in the owners manual that I can find, probably because the owners manual are more generic these days and often there are different engine options. Just swing open the fuel door on your 6.2l and look at the sticker that states "Premium Fuel Recommended", it does not say required, it say recommended, but with LSPI (Los Speed Pre Ignition) so prevelent in todays DI engines with high compression and/or turbo charging, this is really a must. The 6.2l has a compression ration of 11.5:1, I only had a few cars with modified engines back in the day that had compression rations higher than the 6.2l. Extened LSPI can hammer the rod bearings out of an engine and also break piston rings and also damage pistons. Do not be fooled that LSPI is only a problem with turbo engines, the 6.2l rarely runs above 1700 RPM on the highway and the high torque during grade climbs makes the conditions ideal for LSPI, even more so with fuel dilution in the oil.

So I will try to let the data speak for itself. I have been looking at how GM implemented the current 6.2l in these latest round of trucks with DFM and it is crazy how low the engine RPM is on the highway and how much torque the engines are putting out to hold the speed on the highway. Also understand how long it takes to get approximately 11 quarts of engine oil up to at least the engine temperature and even above the engine temperature. 30 minutes of driving at a minimum at temps 50F or below. I have not had a chance to gather data for higher ambient temps yet, but assume at least 20 minutes of driving at 70-80F, again data will show what the timeframe would be.

Suggest you go look over this post in a thread that I provided a lot of data in - https://www.tahoeyukonforum.com/thr...0-000-gm-vehicles.152506/page-29#post-1949528

As far as wondering about Premium fuel vs Regular fuel, I have no data on Regular fuel and I do not plan on gathering it on my vehicle, but look at this graph that is for a 2 hour, 15 minute mostly highway cruise on a reasonable flat area, there were some grades, but nothing major and notice the amount of spark retard in the blue. The red is the engine torque while cruising, notice the amount of torque useage above 75%. While the spark retard values are not signifigantly high, just think about if Preminum fuel was not being used. BTW this is 93 Octane, however, I also realize some areas in the US may only offer 91 Octane as Premium.

 

[Fless]

KMeloney, I appreciate your interest to learn and understand.

Forum tip: don't forget to use the "tag" feature if you want to be sure your target sees the post, or use the "reply" feature like I did here.

To tag someone, start by typing the "@" symbol, then (without a space) the start of the member's name, like this: @KMeloney. Then select the member's name from the picklist that appears.

 

[j91z28d1]

KMeloney, I appreciate your interest to learn and understand. We are and have been sold a bill of goods for a long time. Ever since GM moved away from the older 6.0l in the mid 2000's we have all been forced to SUFFER with AFM, 0W20 engine oil, Auto Stop/Start and all sorts of other foolishness and we are all paying premium money for stuff that is unreliable, breaks often and way too expensive and time consuming to repair. An we are all supposed to like this and smile about it! Even the 6.6l gasoline engines are having failures without the AFM, but they are DI and fuel dilution of the engine oil is a common denominator even with a higher viscosity oil spec for the 6.6l, but these engines are also probably pulling heavy loads on towing on a fairly regular basis.

GM cannot just disable, take off, or recommend the owners do things like turn off the Auto Stop/Start. Just turn off the Auto Stop/Start, the feature does not hold the setting when the engine is turned off, you have to turn it off EVERY time you start the engine. EPA, CAFE and governmental regulatons are all forcing the auto manufacturers to features/add ons like the Auto Stop/Start and DFM. In order for the manufacturers to try to increase fuel economy, they added the Auto Stop/Start and DFM system along with multispeed transmissions with multiple overdrive gears and moved to 0W20 engine oil. But even if GM indicated they should be disabled, we all paid extra for this garbage! None of these things were really added to increase reliability and longivity of the vehicle as this is not as much of a priority as fuel ecomony and checking some boxes that the government required.

Here is the real problem, todays DI gasoline engines while having a much higher power density than older port fuel injected engines really have problem with fuel dilution of the oil. Many 10-20 minute short trips are also likely to keep the oil from getting up to temperature as well. Keep in mind you may start out with 0W20 engine oil, but as fuel is mixed in this oil, the viscosity drops and with the high torque peaks on a regular basis, the fuel diluted oil is just not going to protect the engine. The only way to even start to cook out any fuel in the engine oil is the engine will need to be driven probably at least for 30 minutes at a minimum and more likely 45 minutes to 1 hour. If you tow with one of these trucks or load up a family of 3-6 passengers and all the associated gear, I would not want to rely on 0W20 oil at all.

GM and other manufacturers have provided high power keyfobs and Apps that allow you to remote start your engine and allow the engine to run for up to typically 15 minutes to warm up or cool off the cabin. Doing this is dangerous to any engine, but really bad and tough on DI engines. So if the manufucter tells you not to run the engine for 15 minutes before driving, then why did they give you all the remote start options? Sure you can walk out and start the car as well without the keyfob or App, but you are less likely to do this. I am surprised the government has not outlaw the remote start features due to additional fuel useage and emission output!!! Might be coming to a town near you in the futurer?

Every 10 years in the auto industy there appears to me major changes that impact how and engine is built, operates and runs as well as often some of the changes reduce the reliability and lifespan of the engines. Start back from 1960 and follow each decade and you will see all the changes, many have not been such great ideas. Then the marketing starts to extend mainteance and oil changes. Hell today you have oils that claim they can protect your engine for 25,000 miles and oil filters that claim they can last 20,000 miles. This is not happening on any of my vehicles, especially any of the DI gasoline engines. I am changing oil about every 3000 miles or when the OLM hits 50%.

The problem is nobody drives vehicles under ideal conditions and even if they do, I guarantee you 5-10 years from now everyone that is knowledgeable will say that running oil changes out to 10,000-25,000 miles was foolish! What most people do it put their engines through hell and do not even realize it. What you used to be able to do for your port fuel injected engines is really bad for a DI engine.

As far as Premium fuel, nothing in the owners manual that I can find, probably because the owners manual are more generic these days and often there are different engine options. Just swing open the fuel door on your 6.2l and look at the sticker that states "Premium Fuel Recommended", it does not say required, it say recommended, but with LSPI (Los Speed Pre Ignition) so prevelent in todays DI engines with high compression and/or turbo charging, this is really a must. The 6.2l has a compression ration of 11.5:1, I only had a few cars with modified engines back in the day that had compression rations higher than the 6.2l. Extened LSPI can hammer the rod bearings out of an engine and also break piston rings and also damage pistons. Do not be fooled that LSPI is only a problem with turbo engines, the 6.2l rarely runs above 1700 RPM on the highway and the high torque during grade climbs makes the conditions ideal for LSPI, even more so with fuel dilution in the oil.

So I will try to let the data speak for itself. I have been looking at how GM implemented the current 6.2l in these latest round of trucks with DFM and it is crazy how low the engine RPM is on the highway and how much torque the engines are putting out to hold the speed on the highway. Also understand how long it takes to get approximately 11 quarts of engine oil up to at least the engine temperature and even above the engine temperature. 30 minutes of driving at a minimum at temps 50F or below. I have not had a chance to gather data for higher ambient temps yet, but assume at least 20 minutes of driving at 70-80F, again data will show what the timeframe would be.

Suggest you go look over this post in a thread that I provided a lot of data in - https://www.tahoeyukonforum.com/thr...0-000-gm-vehicles.152506/page-29#post-1949528

As far as wondering about Premium fuel vs Regular fuel, I have no data on Regular fuel and I do not plan on gathering it on my vehicle, but look at this graph that is for a 2 hour, 15 minute mostly highway cruise on a reasonable flat area, there were some grades, but nothing major and notice the amount of spark retard in the blue. The red is the engine torque while cruising, notice the amount of torque useage above 75%. While the spark retard values are not signifigantly high, just think about if Preminum fuel was not being used. BTW this is 93 Octane, however, I also realize some areas in the US may only offer 91 Octane as Premium.

View attachment 451016

curious where this graph come from? if you're able to log, and you log knock count. not they timing retard. there's a lot of retard tables in the tune, anything don't burst knock, to activity knocking.

I do agree, if your dead stock di engine is knocking on 93 just driving around normally. it's not going to be happy 300k miles from now, if it makes it