BTW It was discovered back in the early thirties
by Franklin that heat transfer was more efficient if the cold
air went over the coolest part of the air cooled engine first

David Doshay wrote:

It was figured out by Laplace  in the 1800's that heat transfer is a
function of the temperature difference between the two media.

When the coolest air goes by the coolest water first, and then the warmer
air goes by warmer water, and then finally the hottest air goes by the
hottest water, the slopes are increasing together and thus the highest
temperature difference between the air and water is maintained, thus
maximizing the heat transfer. That is the advantage in the graph  on the
left. In the graph on the right the slopes of the water temperature and the
air temperature approach each other, and thus the temperature difference is
always getting smaller and the total heat transfer will be less.

David

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