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(More speculation) UOAs might become increasingly useless as bearing materials are engineered for wear causing particles to become embedded in the bearing surface. This could be a big problem for people who swear by UOA metal concentration as a proxy for engine wear. There may be a saturation...

My personal opinions: Engines oil grades such as 0w-16 are completely safe in engines approved to run them. Engines which spec these oils have superior lubrication system designs and state-of-the-art coatings which mitigate wear in ways unimaginable even ten years ago due to a superior ability...

I researched cavitation in depth and posted my summary of a paper which discusses the physics of it in a new post https://bobistheoilguy.com/forums/threads/friction-reduction-and-reliability-for-engines-bearings-heig-vd-in-collaboration-with-renault-lubricants-2015.383730/

I found another interesting open access article you guys might find interesting: Friction Reduction and Reliability for Engines Bearings by the Swiss University HEIG-VD in collaboration with Renault. Lubricants 2015, 3(3), 569-596; https://doi.org/10.3390/lubricants3030569 To ensure long engine...

No matter how hard I look I simply don't see too many mitigating factors in engine designs that allow them to use 0w8 engine oils except one: oil pump design. Engine main and journal bearing clearances for many Toyota and BMW simply haven't budged much since the 1990s. The 0w8 and 0w16 oils are...

What's even more interesting about ZDDP is actually how pointless it is to look at concentrations of it to make decisions based on VOA. Researchers have optimized the molecular structure of ZDDP by adjusting the length of alkyl chains and incorporating various substituents. These modifications...

It's because ZDDP film changes form at higher temperatures

That's not true. Read what I just posted earlier about HTHS. In essence, HTHS is something relatively easy to measure but no longer very informative as a metric because it has huge problems. I posted a ton about it above summarizing a paper recently posted by twX

Why even bother with 0w16 and 0w8 then? We can go straight to 0w3 if the AW additives are already perfected for boundary lubrication. Also you wrote about lesser headroom in low viscosiry motor oil, but it should be irrelevant if the base oil is able to resist dipping lower than the engine's MOFT

I doubt that the additive package is that much different from what had been used in the recent past. I suspect the PAOs and Esters are doing the heavy lifting. No evidence either way. Someone posted an article from Nissan in the recent articles section that hinted at this too.

I still want to see more evidence that PAO and Esters are able to help maintain MOFT in these super light oils

I don't have evidence of it yet but it seems that these sub-20 weight oils are able to avoid catastrophic engine damage because they are able to maintain adequate MOFT. In light of everything just posted above, the only way I see 0W-16 and 0W-8 oils achieve adequate MOFT is through the use of...

I see your point. After reading SAE 892154 I think you're still missing the bigger picture. I say this because you're still referring to HTHS viscosity which that publication makes abundantly clear is not a good metric. A very clear key finding in your paper is that minimum oil film thickness...

This should read 5w-30. Typo!

Your charts prove that low viscosity motor oils reduce total engine friction but this does not address wear at all because friction and wear are sometimes not very correlated in the context of internal combustion engines. More support for higher viscosity directly from your linked Toyota study...

Found the smoking gun for the solution to mixed/boundary lubrication buried deep in another paper quoted below: Experimental and Numerical Study of the Mixed Lubrication Considering Boundary Film Strength (Jan 2023) https://www.mdpi.com/1996-1944/16/3/1035 Interesting that past a certain...

What I don't understand is if modern cars operate in mixed/boundary lubrication at lower RPM (due to aggressive gearing) why should it matter much for fuel efficiency to use a low viscosity oil since we aren't reaching into the higher rpm regions (where the engine operates mostly in the...

I found a another really interesting open access paper from 28 April 2024 you guys may enjoy: https://www.mdpi.com/2075-4442/12/5/152 This article is probably as close as it gets to the philosophy of modern oil formulation. The article discusses the challenges of reducing fuel consumption by...

The main thing I kept tripping up on while reading the article is transverse vs longitudinal roughness lay. I don't think there is ever a transverse roughness lay in mass produced engine bearing surfaces.

Dunno; oil is so complicated and I haven't wrapped my head around it. Based on this however your chances of survival might be improved with PAO compared to mineral-based oil but the main thing is this completely destroys the "higher ZDDP = always better" theories floated around here sometimes...