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Posted
11 hours ago, Grumpy Bear said:

Speed postulates that higher viscosity oils have more thickeners to artificially inflate their viscosity numbers. These thickeners lose viscosity under shear, and the result is that not all oils of the same viscosity have the same shear stability.

 

He is not saying that an SAE *W20 will have more viscosity than a *W40 due to MORE VII polymers. He is saying that although multiple *W40 may post in the PDS the same or similar 100 C and 150 C viscosities that the blenders choice of modifier TYPE and AMOUNT to get his chosen base to grade will not give identical real world viscosities in shear and at temperature. All will pass the SII test but not all will pass the 100 C HTHS (unpublished value) testing the blender does and relies on to get the required by law "percentage improvement' referenced to his last great work. 

 

Tis the problem with the lie. Once told others are required to support it. :banghead:

  • Like 2
Posted
12 hours ago, Grumpy Bear said:

www.enginelabs.com/news/what-i-learned-today-bearing-clearances-vs-oil-viscosities/

 

 

www.enginelabs.com/news/oil-viscosity-can-the-numbers-be-misleading/

The Big Lie…

Coming full circle to the reason Lake discusses the Porsche engines in particular. Based on the 2000 samples in the SPEEDiagnostix database, increasing the oil viscosity in these engines, even those run on the track, showed no significant difference in results.

 

The smoking gun was in the oil chemistry. That is where the data shows higher instances of more wear. Molybdenum was the key; the higher the amount, the less the wear. Speed postulates that higher viscosity oils have more thickeners to artificially inflate their viscosity numbers. These thickeners lose viscosity under shear, and the result is that not all oils of the same viscosity have the same shear stability.

 

Having enough viscosity is the most important characteristic, but according to Speed, once that required viscosity level is reached, additive chemistry matters more than additional viscosity. Speed also states, oil pressure problems on the racetrack aren’t a viscosity problem; it’s an oiling system problem. Running a thicker oil is just a band-aid for an underlying oiling system problem.

 

Which has made me wonder with the various engine failures of a few brands in the last few years, is it sub par materials such as lifters etc causing failures, or bearing clearances on the crank etc or perhaps bad designing of an engine physically or causing too much load on the components due to the hp/torque they can push out of them. Or is the oil viscosity and additive package of current oils or a lack of oil flow by an oil pump not able to supply sufficient oil at idle or under high load at low rpm. Or is it every item I listed that combined together has pushed the limits so far to the left that there is hardly a margin of safety left and add in some fuel dilution and too long of an OCI and premature engine failure is the result ?. 

Posted
9 hours ago, Chuck FB said:

Or is it every item I listed that combined together has pushed the limits so far to the left that there is hardly a margin of safety left and add in some fuel dilution and too long of an OCI and premature engine failure is the result ?. 

 

Yes :) 

  • Like 1

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