And what you got was commentary on formulation and the contribution of VII to volatility, and even the tradeoff between different VIIs used. Even the lowest volatility 0w-40 will be higher than the lowest 5w-20. Therein lies the inherent compromise for only caring about HTHS holy grail.
Yet, two experts in this thread have said increases in viscosity/hths only decrease wear.
Yeah, VII type and concentration is part of the formulation - just like I mentioned. There are plenty of oils that have higher HTHS and low Noack. So that "trade off" can be avoided if you chose the right oil ... so "oil is oil" isn't a thing in many cases like that.
It does reduce wear, and now you're trying to connect a metallurgy/manufacturing flaw to claim higher HTHS viscosity doesn't reduce wear when there mountains of evidence that say otherwise.
Highest HTHS
What that post mean? ... the W grade doesn't have much to do with Noack.
Now you're putting words in my mouth. See post 31. But if you want to take your generalization to the edge of the graph and beyond, you (as usually) don't need anyone else's help.
This isn't really a "wear" issue, it's a metallurgical one that, with the evidence I've seen presented, points to improper heat treatment of the roller/pin assembly, that eventually fails, leading to the needles working a groove in the roller or pin, which, when it gets deep enough, results in the needles piling up, the roller seizing and then the roller and lobe working at destroying each other.
post 83 was only 9 minutes ago and you already forgot what you said?
Here's your post 31. What's that have to do with the fact that higher HTHS gives more MOFT and reduces wear? You are tying to correlate a manufacturing issue with now what seems like a claim that higher HTHS doesn't reduce wear.
Your post 85 is cryptic ... makes no sense without context. And what KV100 is connected to those W ratings?
Fragile valvetrain for which the manufacturer has prescribed 0w-40.
"Wearing a groove" because the metallurgy is bad. Parts in mostly boundary and mostly mixed lubrication need adequate metallurgy and surface hardness as part of there anti-wear design ... along with an adequate HTHS viscosity.
Whatever KV100 follows that magical HTHS.
That is incorrect. The same valvetrain has spec'd 0W-20, 5W-20 and 0W-40 depending on what it is fitted to. The 5.7L and the 6.4L take the same lifters.
We've seen heat treatment issues with valvetrain components before. GM had the famous "flat cams" debacle in the early 1980's as a result of improper heat treatment, Honda has recently had lobe delaminations for the same reason. Cummins had this issue on the ISX. You have surfaces that require a certain level of hardness to maintain durability, and if that hardness isn't properly applied, it fails, exposing softer metal that isn't meant to be subjected to the pressures that the hardened surface was designed for. That is the case here.
Whatever that means, lol.
Sure, if the right oil is used in a specific multi-viscosity. The easiest way to get that magical HTHS viscosity is go up a grade if using a xW-20 or less, and go up from xW-30 to a xW-40 or 50 if tracking or going gonzo on really stressing the engine.
Or make the design with some margin by increasing contact area. Reduces load. If your design doesn't allow for manufacturing variability, the design is the problem.
Sure, but in that specific case it looks like metallurgy is the root issue. Have they made design changes like increasing contact area, reducing valve spring load, etc?
If all modern engine failures are traceable back to metallurgy, then the quest for viscosity as a wear cure falls apart though.
