One would think that Gray is just a mix of Black and White. But this is not true for many paint applications. As it is a very flat range of gray. Many paint companies mix Gray with out Black some use left over colors of several batches to mix shade or tones of Gray.
Chevrolet may have been in the mode of mixing the engine Gray from leftovers.
But even if not it is very common to have a bit of Blue tint in a gray paint mix to bring up the tone.
If this might be so for the Chevrolet engine Gray even if a very slight amount to some in the right light it would appear with a slight blueish affect.
The one original engine I have seen to me while it is Gray does have a slight Blueish tinge with age and fading from time and washing whether or not this was stronger 60 years back I could not say.
I would prefer a not Black/White mix but more the very slight tinge of Blue effect in my Gray to stand out to the right eye. But I do not want a Blue engine.
