From the article...
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and that lower viscosity helps free up some horsepower because the oil pump doesn’t have to work as hard to move the oil throughout the engine.
They fell for that one...
The amount of extra oil pump shaft power between two oils of different viscosity, at relief is zero...assuming an oil is thin enough to drop out of bypass, and assuming a 10-20 psi difference between the two, there's 50-100W difference in oil pump drive power...turn on the headlights for similar effect.
It's the myth of thinner oils, that is perpetuated here, and obviously there.
Where the thinner oils release power is in that crank/cam spinning in the bearings and pistons moving in the cylinders all consume less horsepower on thinner oils.
THAT's the power that manufacturers are chasing with thinner oil (and TBC on cylinder walls, advanced oil cooling/heating etc.).
For some reason, someone at some stage said it was oil pump drive power (Mobil have, and the usual suspects have latched onto THAT too)....it's wrong...it's there, but maybe a tenth part of the total.
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The myth of improving protection by increasing viscosity can actually be harmful to your engine in some circumstances. As much as 70 percent of the wear on an engine occurs at start up. That’s because while the engine has been off, the oil has an opportunity to drain back into the pan and away from the areas it needs to be. Obviously, you want to get oil back to the bearings, the cylinder walls and all the way up to the valve train as quickly as possible to bring the protection back where it should be.
It's warm-up wear, not start-up.
The engine wear typically is taking place in the period that the oil has fully developed oil flows and pressures, not the couple of seconds between turning the key, and oil seen at the cam.
Industry standard wear test is on a cool engine, fully "lubricated", just at the wrong temperatures for the lubricant to be functioning correctly.
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So while a thicker, higher viscosity oil does usually provide a stronger film surface to protect the bearings, that only applies once the oil is in place and ready to do its job. But thicker oil is more resistant to flow, and it takes longer for the oil pump to push it through the oil galleries to where it needs to be. A thinner, lower viscosity oil flows more easily right at startup and gets to those critical areas more quickly. Because of that, a thinner oil can actually do a great job of reducing the wear an engine sees when it is first cranked.
Given that the first start of the day is dry galleries, and the viscosity of the air in the galleries is effectively zero, the PD pump will shift pretty much the same volume of oil per revolution up to the point that the galleries are charged.
Unless the oil chosen is completely inappropriate to the ambient at hand (W rating), oil will reach the remote points about the same.
If an SAE 30 is used at 100F, a 5W20 won't fill the galleries any faster.
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So the obvious question becomes how thick is too thick? Or, how thin is too thin? After much research, Speed says a good rule of thumb is to monitor the oil pressure at idle when the engine is up to operating temperature. Consider 20 pounds of hot oil pressure at idle to be a safe minimum, so start with your usual oil viscosity and lower the viscosity at each oil change until you get to 25 or 30 pounds idle pressure. Just make sure you use a high-quality oil that won’t lose film strength under normal operating temperatures.
Don't know how you do that.
For a given geometry and load, minimum oil film thickness is completely related to high shear viscosity...drop the viscosity, drop the MOFT.
If they are now talking about lubricants that are better in boundary lubrication, that's not the correct term, and how does the consumer verify it (other than buying their oil ???)
