@fredtufts
0W20 is adequate and clearly works in most cases. But again 0W20 was developed for better fuel efficiency not necessarily better engine protection. Not many things that offer better fuel economy tend to be durable and long living or help with the overall reliability of the engine or now the automatic transmission with Ultra Low Viscosity automatic transmission fluids.
Part of the problem is the auto manufacturers cannot just change things that the engines/vehicles were certified with by the EPA or even when it comes to safety. In a way I am surprised the EPA allows Remote Starting if they are so worried about fuel economy and emissions!
So based on some SAE research it appears that 0W20 was developed mainly for increases in fuel economy but to try and keep the same basic protection of 5W30. So 5W30 does not have much of a jump in HTHS (High Temp/High Sheer) when compared to 0W20. There is a difference, it is just not much. If you want a jump in HTHS, the next step is 0W40. I have not compared to 10W30, but the problem is so much of today's engines are now "hydraulically" controlled for valvetrain timing and behavior, I feel that the 0 weights are less likely to cause any unusual behavior with the valvetrain control.
As I have stated many times, after running a bunch of data logging on my 2024 6.2l Yukon Denali XL, I found it concerning how often and for how long the engine loading at lower RPM's pushed the engine loads into the 70-100% range while cruising on the highway. 0W20 was able to handle it, but probably in more ideal conditions. Once fuel contaminates any oil, it viscosity and cushioning ability decreases. As an owner/driver, you cannot really tell if and how badly the oil may be fuel contaminated. Fuel contamination of the engine oil is a fact of life more so with Direct Injection engines. It can happen with port injection and turbo engines as well.
Bearing loading and oiling tends to be challenged either with extremely high RPM's or under high engine loading, especially at lower RPM where you are close to lugging the engine. Towing is also an extreme sport, while I have not experimented with the Tow Mode on my truck, I have to assume the TCM (Transmission Control Module) behavior is changed to delay shifting until higher RPM's and to not put the engine under constant heavy loads at lower RPM's. I know from towing with my 2005 6.0l Yukon even an empty enclosed trailer how much the air resistance will load the vehicle. Getting around 10 MPH when towing with anything is not unusual.
I just think the 6.2l with the TCM programming trying to squeeze 21-22 MPG out of 6000 brick is pushing the limits on the oil if it is not 100% fresh. I also think that the 0W20 is more likely to be consumed much quicker than 0W40 and once oil consumption as started, the oil supply is lower, so less cooling, less tolerable to fuel contamination, faster to break down because of just level volume. As a good friend of mine from the EPA used to say all the time, "The solution to pollution is dilution". So you need more oil to dilute the fuel in the sump, less oil in the sump the fuel dilution has a greater impact.
There are cases of small turbo charged Honda engines diluting the oil with so much fuel that there are 1-2 more quarts of oil/fuel mix in the crankcase. Why do these engines not fail at the rate of the 6.2l? I believe it is because the vehicles are much lighter and the engines are not put under extreme Low RPM/High Load conditions under normal driving conditions. Sure the turbo gets hot and needs to be oiled, but at the end of the day, driving a lighter Honda around town and on the highway without putting your foot hard into the throttle probably keeps the engine loading under 50% most of the time.
Totally different animals and operating conditions. We are driving small school buses that the engine rarely operates above 1700 RPM unless accelerating or passing. The higher 3000-4000 RPM's are actually easier on the engine bearings, especially with the 2 stage oil pump where the engine oil pressure jumps to around 70-80 PSI somewhere around 3000-3500 RPM.
I am just not comfortable with anything other that 0W40 in my engine, GM has come out and pretty much indicated there is not a problem running this oil in these engines based on what the Camero and Corvette uses as well as what he NHTSA Recall 25V274 states. I was aware before the Recall was announced that 0W40 would cause no negative effects to pretty much any engine speced for 0W20.
With the power output density of these modern day engines with Higher Compression Ratios, Direct Injection, Low Speed Pre Ignition problems and higher operating temperatures changing the oil often and running something higher is viscosity than 0W20 engine oil is clearly in my bag of tricks. Changing oil at 50% of the OLM is my recommendation. Some may say this is a waste, but even if your main and rod bearings survive, the roller lifter are NEXT in line to be a problem. This is why clean oil with lower fuel dilution is critical to modern engines. While you can analyze the oil all day long and have it say you can run to 10-15k oil change increments, you are paying $40-$60 for the oil analysis, why not put that money toward more frequent oil changes to keep the engine cleaner and eliminate higher percentage of fuel dilution in the oil.
Also consider something other than the 0W40 Mobil 1 Supercar oil, it is expensive. While there are plenty of other good 0W40 oils on the market that may not be "Officially" Dexos approved, check and see if the oil vendor you like has Dexos approved oils, if they do, they know what is required for Dexos approval but may choose for many reasons not to get their 0W40 approved due to costs, demand and other factors. The main thing the oil needs is a lower Sodium level to help with the reduction of Low Speed Pre Ignition. I am sure you can search and find someone that has performed an oil analysis on non Dexos approved 0W40 and you will be able to see the sodium level. Of buy 1 quart of an oil you would consider using and send a sample for analysis and see what the additive pack values look like. Probably cost you around $50-$65, far less than a full oil change of Mobil 1 Super Car oil.
