not sure how to word this... (deleted three times so far...)
I am curious if the relative mass and/or solid cast iron nature of the objects involved would be of effect. In other words, if the modern materials are engineered with the modern machines in mind, could the benefit to using them be reduced on systems that they were not designed for.
I say this because I know from personal experience, that companies today min/max their engineering. They will "de-engineer" something that lasts longer than a warranty. I can imagine a company doing viscosity tests and determining that their product is performing above necessary specs and reduce the key costly ingredients until they are with specs.
There was a different mindset prior to WWI..... Companies would compete to be "the best" not JUST the most profitable. I personally think that it was the governments of the world gearing up for War with the "give me the best price as long as it meets these specs" that was the beginning of the end...