Can anyone explain tthis to me:

A car engine is run at an optimum temp of 250-280F why?

An airplane engine is left to dry in the wind with no regards to the temp.

A boat pours cold water through the engine, and dont reach much more than lurke warm.

How come they dont have to operate in the same temperature range?

Why is it so important that a car is run at the correct temp, but the other two types of engines are "overcooled"?