And none of that matters ,,,, because the issue with the whole warm-up or not to warm-up thing is not about the oil or bearing wear ,,,, its about piston ring wear ,,, and piston ring wear is more affected by coolant temperature than the oil temperature.
There are work trucks and police cars that get literally thousands of idle hours on them every year (including the police Tahoe's) its not the bottom end/ main bearings/ rod bearings in those that cause the engines to get replaced, its that they start smoking and burning oil because the upper compression ring gets worn and the oil control rings gets clogged.
The issue the 6.2 has that opened the NHTSA investigation (remember that, the topic of the thread) revolves around bearing failure, aka , not related to the whole warm-up or not to warm-up thing.
Yes extended warm-up is bad, but it isn't the freaking cause of, or even a contributing factor to, the issue the 6.2 has that's causing the NHTSA investigation.
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Warming up the engine without driving the vehicle adds to a pretty substantial increase in fuel dilution of the engine oil. Add this to the 0W20 engine oil, the fact that the 6.2l is running the 2 stage oil pump (the 5.3l L84 dropped the 2 stage pump) add in the High Torque/Low RPM operation, Auto Stop/Start, DFM and LSPI and oil consumption where these engines are being run chronically low on oil, this ALL has to do with premature bearing wear. My 6.2l operates about 28 PSI in gear at idle, this is also not with 0W20 oil, this is also not a Summer high temp long drive sitting in Metro rush hour traffic, what do you think the oil pressure might be if 0W20 was being used and was thinned out with fuel, it sure would nto be higher than 28 PSI. Even at 28 PSI, I can hear the front main and #1 rod bearing screaming.
All the fleet idling you are talking about is idling with fully warmed up oil, not part of the concern here, but it could still lead to some fuel dilution of the oil. But most fleets are smart enough they change the oil more frequently than a typical customer driving a daily.
Lets not forget the fact that we have all but abandoned the lifters and camshaft problems at this point. The roller bearings in the lifters are a weak spot when the oil gets thinned out as well. The tiny needle bearings inside the lifter rollers have a lot of loading put on them and the thin oil that is recommended is probaby borderline, fuel contaminated oil, well good luck.
You seem to be missing the POINT again, I am sure others are starting to follow along.
Bearing failures before the first oil change, I have no specific data on these problems, could be a parts or assembly problems, could be the lack of Preminum fuel and people getting too used to the remote start and warming up these vehicles, DFM fully operation and Auto Stop/Start fully operational. Hell has anyone even check the oil level is these engines that failed at under 7500 miles, they might be close to 2 quarts low on oil.
UNDERSTAND we have had a lot of recent complaints and what season are we in now, WINTER. We have had a number of Polar Vortexs hit areas that are not typically hit with the cold temps we have been seeing in much of the US. Some of these owners might have been caught off guard without ice scrapers would just start the truck with the remote and allow the engine to idle for 15-20 minutes, who would not want to get is a warm truck when it is 0F outside. If the ambient temps are 0F, what temp would the oil get up to after a 15 minute no load idle, not very high. Some of the failures happened before the WINTER temps hit, but cold weather is hell on the engine oil in these trucks on a good day.
Pay attention to or at least UNDERSTAND the OIL TEMPERATURE and how far it lags behind the coolant temperature. Forget the COOLANT TEMPERATURE, the coolant will heat up within the first few miles of driving, the oil will be lucky to be 10-15F above the ambient temperature after 3 minutes of starting the truck and driving. Oil temp may barely move if you start the engine and just allow it to idle.
All the bearing failures after the first oil change are not likely faulty components or assembly issues. Oil starvation and/or oil breakdown/fuel dilution, add LSPI and 2 quarts low on contaminated 0W20 which is lucky to be -10W10 by the time the crankcase is loaded with fuel, good luck!
Buy into what you want, cold engines under no load take longer to warm up than an engine that is driven, oil typically takes at 2+ times or longer to get up to a resonable temperature and may even take as long as 15+ minutes to even match the engine coolant temperature.
Go back and read my prediction for the outcome of the NHTSA "investigation", not holding out any hope there will be whole engine replacments, GM will try to pass most of the problem off to how the vehicle was driven and maintained, and in part they would be mostly correct.
