Yep, I knew of that website and read the whole thing. I can't confirm or deny any of his methods or results. I can understand what is being said, but my take away is that the oils are based on "shear" testing and almost dismiss the assorted additives. I have to question why they used ZDDP in the earlier oils for wear protection when I take awy from the discussion that the wear protection qualities of the additives are not as important as the "shear" ratings of the oils.
Next, does his means of oil testing comply with the API form of oil testing/rating? Here is a load test used on oils based on a method Timken bearings use and the results:
http://www.animegame.com/cars/Oil Tests.pdf
Then, his analysis of using a thinner oil can be better seems to be contridicted by this statement, "
Viscosity and Wear Prevention
- This same molecular friction prevents the oil from escaping too quickly when two engine surfaces in relative motion are brought closely together under pressure. This inability of the intervening oil to escape quickly and its level of incompressibility hold the two surfaces apart and prevent wear, a process that is termed hydrodynamic lubrication. The higher the viscosity, the greater the attraction of the oil molecules and the greater the wear protection."
So in my mind, and my choice, is a
thicker oil, not thinner - like 10W30 or my choice of 15W-40.
The above info, and more, is found here:
https://www.machinerylubrication.com/Read/30329/engine-oil-quality
The article sited also seems to indicate that there can be no metal-to-metal contact due in part of the incompressibilty of the oil film - so as long as an oil film is present. That may be great in a closed system, but that is not the reality of an engine - with oil leaks all over, ie the flow of oil out the bearings, out from under hydraulic lifters/cam lobes, etc.. That's were ZDDP can come into play -
"Zinc dialkyldithiophosphates (ZDDPs) have been used as a multi-functional additive in engine oil for over 50 years [9]. ZDDPs mainly function as an anti-wear additive; however, they also impart oxidative and corrosion resistance to the base oil. ZDDPs also exhibit mild EP (Extreme Pressure) characteristics. As an anti-wear agent, ZDDPs react with surface asperities (surface roughness) to reduce metal-on-metal contact.
When applied loads are high enough to collapse the thin-film on the surface, ZDDPs react with the entire metal surface to reduce wear. In a general sense, the anti-wear film can be said to be composed of ZDDP degradation products; the thickness and composition of the products are directly influenced by temperature [9]. The nature of the ZDDP film has been extensively studied; however, no analysis provides a concise description of the film within automotive lubrication regimes."
This info above is found here:
https://www.ilma.org/PDF/ILMANews/2017/AAAreport.pdf
along with a wealth of other info
to include oil test methods.
My conclusion? Who do you trust/believe - an independent home scientist and his methods, or the actual American Society for Testing and Materials (ASTM) standardized tests that meet the American Petroleum Institute (API) and International Lubricant Standardization and Approval Committee (ILSAC) specifications.
Of course you could also use the real world suggestions of other "old car" owners who have experienced no issues with their choice of oils and/or additives.
Which is the best oil to use? I don't think there will ever be a single answer to such a question. :thumbsup: