Who put this stupid idea in your head?
I mean...


100% true

Some info about viscosity: water, you know, H2O, has a viscosity of 1 cSt at 20c at sea level - a standard science condition
(just forget about the cSt, its no more than a unit)
As far as I know they actually used water as the reference back in the day when they were figuring out about viscosities.
2 cSt is twice as thick, IOW its a linear unit.
10W-30, when hot, is usually around 10 cSt, so 10 times thicker than water and that is HOW IT SHOULD be.
A hot 5W-40 oil is around 13 cSt, you will notice the difference pouring out your hot engine.

 

Good info. , on the 40 weight I used it sheared down to 11.4 cst, not uncommon in some 40 weight brands/weights, so when it came out hot it was hard to distinguish much of a difference from it and an unsheared or mildly sheared 30 weight. Perhaps if you rubbed it between your fingers, but visually from sitting under a vehicle it doesn't look much different.

 

At that point it's all about it's sheer strength. It can appear runny at temp, but still hold the surfaces apart from each other which is mainly what it's trying to do.