If the previous owner specifically make sure they do not know about that because they made a quick cash grab, how exactly do you imagine they should know about this?
I understand now that TO exclusively was thinking about weight, while that is only one of many things that are limited by the surface to volume scaling.
The whole issue with that is not only about weight, that hardly scratches the surface. Heat transfer, friction, radiation, mass transfer, etc. all get limited by this in some way and are FAR more consequential than weight alone.
It has next to nothing to do with pressure, let alone temperature drop due to expansion. There are 2 things:
When each one quantity of cold and warm air mix, the temperature of the mixture is almost exactly the midpoint (average), as the heat capacity is almost a constant.
Vapor pressure of the water is a function of temperature and scales FAR more than linear.
So now when the hot, humid (burned hydrocarbon) air of the exhaust mixes with cold air the temperature drops a bit, but the vapor pressure drops massively. When conditions are right, the vapor pressure is now below the amount of vapor pressure that is actually present -> condensation.
Okay, but the question remains about what he drinks elsewhere.