Hard to argue with physical tests. I must admit I was in the category of “ this is what we have always used, high zinc is a must”. This is a nice consolidated pice of the whole blog.
Interesting to see Valvoline at the top of the list. That's what I use, not so much from "always done it this way" as 40+ years of old engines that run forever and are completely clean if opened up.
I don't know what the zink level or shear compression is in Valvoline Conventional, it must be good, has worked from break in on in countless engines. If the law required them to lower the Zink content, they clearly put something else in that kept it working, or high Zink was not necessary in this quality oil blend. . It'll take more than published Zink numbers and the latest consensus to induce me to change what has always worked. "If it still ain't broke- why 'm I fixin' it"?
) in college a discussion about the geopolitical origin of oils and I remember the same thing, one area was better oil ( better grade ). Can’t remember where is was but probably the same information. I think the additive package is important in current oils nowadays. I haven’t heard anything about where it comes from as being important in a long time
