@Vladimir2306
I think the point you are missing is fuel contamination is like a Yo-Yo. Depending on how the vehicle is used, the outside ambient temperatures and the season you are currently in, the fuel dilution percentage is always a moving target. Make a bunch of 10-20 minute drives in the Winter and never fully warming the oil up, fuel percentages will be high, then take a 1-2 hours highway trip, the fuel can be "cooked" out of the crankcase, maybe not all the fuel, but the percentage will be reduced. Adding make up oil for oil consumption will CLEARLY reduce the fuel dilution percentage. Use the vehicle mainly for 45+ minute trips, fuel contamination will be a much smaller problem then remote starting the vehicle and allowing it to warm up at idle and making a bunch of trips between 10-20 minutes at a time. Once you change the oil, you RESET the baseline and have very little fuel contamination, probably a small amount of residual oil with fuel left over in the oil cooler, oil cooler lines and some small amount that has not drained out of the engine.
During these times of higher fuel contamination, the fuel in the oil will reduce the oil viscosity and any safety margin will be lost. Given the bordeline protection 0W20 oil provides for these engines they way they are loaded on the highway, fuel dilution is a factor that may not be as much of a problem for smaller engines and smaller vehicles.
Case in point I had a 1987 Buick Grand National Turbo 6 cylinder that cruised at 70 MPH at 1800 RPM on the highway. BUT this car was 1/2 the weight of these trucks and far more areodynamic, the transmission was a 4 speed automatic with only 1 Overdrive gear. These engines ran 10W30 engine oil and had no issues running lower RPMs on the highway because the engine was not constantly hittig 80%+ loading on a regular basis. Probably running at an average of 50% loading, I have no data on this vehicle because OBDII was in its early stages and there were not low cost ways to aquire data. Also understand if this engine went to 100% loading on the highway, the vehicle could go from 50-70 MPH in under 2 seconds!
As for your concern that a slightly higher oil viscostity will not make its way to the bearings given the oil passage size, this is a non issue. There are no magical smaller oil passages or overly tight bearing clearances. Bearing clearances have not signifigantly changed for years. And again, the exact same engine platform has different specs for oil viscosity depending on the application. Part of the "application" is how many of the specific platforms are being sold, nothing to do with performance, protection or reliability. While you are not in the US and did not grow up in the US you may not understand the stupid rules and restrictions that non techinical goverment employees put on automotive industry for the past 50 years.
BUT as of this week, this is in the process of changing for the better! If we are lucky, DOD/DFM may be a thing of the past.
I think the point you are missing is fuel contamination is like a Yo-Yo. Depending on how the vehicle is used, the outside ambient temperatures and the season you are currently in, the fuel dilution percentage is always a moving target. Make a bunch of 10-20 minute drives in the Winter and never fully warming the oil up, fuel percentages will be high, then take a 1-2 hours highway trip, the fuel can be "cooked" out of the crankcase, maybe not all the fuel, but the percentage will be reduced. Adding make up oil for oil consumption will CLEARLY reduce the fuel dilution percentage. Use the vehicle mainly for 45+ minute trips, fuel contamination will be a much smaller problem then remote starting the vehicle and allowing it to warm up at idle and making a bunch of trips between 10-20 minutes at a time. Once you change the oil, you RESET the baseline and have very little fuel contamination, probably a small amount of residual oil with fuel left over in the oil cooler, oil cooler lines and some small amount that has not drained out of the engine.
During these times of higher fuel contamination, the fuel in the oil will reduce the oil viscosity and any safety margin will be lost. Given the bordeline protection 0W20 oil provides for these engines they way they are loaded on the highway, fuel dilution is a factor that may not be as much of a problem for smaller engines and smaller vehicles.
Case in point I had a 1987 Buick Grand National Turbo 6 cylinder that cruised at 70 MPH at 1800 RPM on the highway. BUT this car was 1/2 the weight of these trucks and far more areodynamic, the transmission was a 4 speed automatic with only 1 Overdrive gear. These engines ran 10W30 engine oil and had no issues running lower RPMs on the highway because the engine was not constantly hittig 80%+ loading on a regular basis. Probably running at an average of 50% loading, I have no data on this vehicle because OBDII was in its early stages and there were not low cost ways to aquire data. Also understand if this engine went to 100% loading on the highway, the vehicle could go from 50-70 MPH in under 2 seconds!
As for your concern that a slightly higher oil viscostity will not make its way to the bearings given the oil passage size, this is a non issue. There are no magical smaller oil passages or overly tight bearing clearances. Bearing clearances have not signifigantly changed for years. And again, the exact same engine platform has different specs for oil viscosity depending on the application. Part of the "application" is how many of the specific platforms are being sold, nothing to do with performance, protection or reliability. While you are not in the US and did not grow up in the US you may not understand the stupid rules and restrictions that non techinical goverment employees put on automotive industry for the past 50 years.
BUT as of this week, this is in the process of changing for the better! If we are lucky, DOD/DFM may be a thing of the past.
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