Buster,
Well, it's just a matter of resolution. If you can pull the engine apart, as is done in sequence testing, you can determine where the wear is occurring, and how severe it is. However, there are plenty of papers out there where physical measurements have been correlated to ppm wear results. It's just that when you measure the oil, you're getting an average of every possible wear source.
The reality is that most issues are detergent and dispersant issues. If those additive packages are correct, most problems with most oil in most engines are solved. (That's why pretty much anyone can choose base oils, and then poor in an additive kit from Lubrizol and make a good oil.) It just takes money and some lab beakers. Most of the time it works just fine.
In studies of wear vs. viscosity, or wear vs. HTHS, the conclusion is generally that it is the detergent and dispersant packages that are most important, along with other high pressure and anti-wear additives. You can only measure real differences in wear vs. viscosity or HTHS when the additives are held constant. And, conversely, when the additives are degraded, either by depletion (run time) or contamination (fuel, soot) wear goes up. And where does it go up, well in the boundary and mixed lubrication regimes, where the hydrodynamic film has collapsed. If the dispersants don't carry the debris away to the filter, you get more wear. If the contaminants neutralize or dissolve the high pressure anti wear layers, you get more wear at the cams, chains, followers ... etc.
The difference in different oil formulations is all in the additives. For many engines, who cares. The environment is just not that severe. In other engines, where the environment is severe (turbos, DI, high HP, high rpm) the difference between oil formulations and chemistry can be seen in the light of day. I suspect that this bothers some oil formulators, which is why they make excuses for their high wear numbers in some applications.
BTW, none of the sequence testing I am aware of uses fuel diluting engines.
Well, it's just a matter of resolution. If you can pull the engine apart, as is done in sequence testing, you can determine where the wear is occurring, and how severe it is. However, there are plenty of papers out there where physical measurements have been correlated to ppm wear results. It's just that when you measure the oil, you're getting an average of every possible wear source.
The reality is that most issues are detergent and dispersant issues. If those additive packages are correct, most problems with most oil in most engines are solved. (That's why pretty much anyone can choose base oils, and then poor in an additive kit from Lubrizol and make a good oil.) It just takes money and some lab beakers. Most of the time it works just fine.
In studies of wear vs. viscosity, or wear vs. HTHS, the conclusion is generally that it is the detergent and dispersant packages that are most important, along with other high pressure and anti-wear additives. You can only measure real differences in wear vs. viscosity or HTHS when the additives are held constant. And, conversely, when the additives are degraded, either by depletion (run time) or contamination (fuel, soot) wear goes up. And where does it go up, well in the boundary and mixed lubrication regimes, where the hydrodynamic film has collapsed. If the dispersants don't carry the debris away to the filter, you get more wear. If the contaminants neutralize or dissolve the high pressure anti wear layers, you get more wear at the cams, chains, followers ... etc.
The difference in different oil formulations is all in the additives. For many engines, who cares. The environment is just not that severe. In other engines, where the environment is severe (turbos, DI, high HP, high rpm) the difference between oil formulations and chemistry can be seen in the light of day. I suspect that this bothers some oil formulators, which is why they make excuses for their high wear numbers in some applications.
BTW, none of the sequence testing I am aware of uses fuel diluting engines.
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