I am curious as to how useful the engine temperature sensor actually is. It tells you the coolants temperature obviously, but I have read that the engine actually operates hotter than the coolant. For example, oil temperature can vary from 90 degrees Celsius to around 120 depending on engine load.
Hypothetically speaking, if an engine's coolant was replaced with pure or highly concentrated anti-freeze which does not transfer heat as effectively as water, how would this affect the engine's actual temperature?
I would imagine it would increase higher than normal but would the sensor show any indication of this, or would the engine be overheating without the user ever knowing?
Thank you all for your time.